Glossary

Glossary

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  • WAP: WAP stands for Wireless Access Point. A device that allows connectivity between computers with wireless network adapters to create a wireless network.
  • 1080i: 1080i represents 1,920 pixels displayed across a screen horizontally and 1,080 pixels down a screen vertically. This arrangement yields 1,080 horizontal lines (pixel rows), which are, in turn, displayed alternately. In other words, all the odd lines are displayed, followed by all the even lines. This means that only 1/2 the resolution (540 lines or pixel rows) is displayed on the screen at any given time - in other words, only 540 pixel rows are displayed at any given time.
  • 1080p: 1080p represents 1,920 pixels displayed across a screen horizontally and 1,080 pixels down a screen vertically. However, unlike 1080i all pixel rows or lines are displayed progressively, providing the most detailed high definition video image that is currently available to consumers.
  • 16x9: 16x9 represents a screen aspect ratio of 1.78 units of horizontal width to 1 unit of vertical height, which is usually expressed in terms of 16 units x 9 units. 16x9 is the standard aspect ratio for originally produced HDTV content, thus all TVs now sold have this aspect ratio. TV programming or video content transmitted or fed to a TV that is not in the 16x9 aspect ratio will appear on a 16x9 aspect ratio screen with black bars on the top and bottom of the image or black bars on either side of the image.
  • 3.5mm Plug/Jack:  Also referred to as a 1/8 inch, auxillary input, mini stereo, and mini phono. These are commonly found on portable devices like newer smartphones, tablets, laptops and computer sound cards. They are used to transmit audio.
  • 480i: 480i represents 480 lines of resolution scanned alternately - with all odd lines scanned first, then all even lines. 480i is also commonly referred to as standard video resolution.
  • 480p: 480p represents 480 lines of resolution scanned progressively. 480p is similar to the same resolution of standard broadcast TV (and is referred to as SDTV or Standard Definition Television), but the image is scanned progressively, rather than in alternate fields.
  • 4k: 4K refers to one of two high definition resolutions: 3840 x 2160 pixels or 4096 x 2160 pixels. 4K is four times the pixel resolution, or twice the line resolution (2160p), of 1080p (1920 x 1080 pixels) that is one of main current consumer high definition resolution standards. The other high definition resolutions currently is use are 720p, 1080i or 1080p. 4K is now officially designated for consumer products as Ultra HD or UHD, but is also referred to at times, such as in professional or commercial settings as Ultra High Definition, 4K x 2K, or Quad High Definition.
  • 720p: 720p represents 1,280 pixels displayed across the screen horizontally and 720 pixels down the screen vertically. This arrangement yields 720 horizontal lines (pixel rows) on the screen, which are, in turn, displayed progressively, or each line displayed following another. This means that all 720 pixel rows are displayed at all times. Although 720p is high-definition, it takes up less bandwidth than 1080i or 1080p.
  • 802.11n: 802.11n is a wireless or Wi Fi standard that was introduced in 2007. It supports longer range and high wireless transfer rates compared to its predecessors 802.11a/b/g.

    802.11. supports Multiple In and Multiple Out (MIMO) data transfers, which transmits multiple streams of data at once. This doubles the range of a wireless device.

    802.11n also supports data transfer speeds of over 100Mbps, compared to the older versions which was up to 54 Mbps.
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  • A2DP: A2DP (Advanced Audio Distribution Profile) is used for streaming stereo music wirelessly yp headphones or speakers over Bluetooth.
  • ABS Filament: Acrylonitrile  Butadiene Styrene (ABS), is a 3D filament that is commonly printed at 210-240 degrees C, with a heated bed of 80 degrees C or more. Requires controlled temperature unlike PLA.
  • ARC: Audio Return Channel (ARC) is a very practical feature that has been introduced in HDMI ver1.4 and later versions. What this function allows, if both a home theater receiver and a TV have HDMI ver1.4 or later version connections, and offer this feature, is that you can transfer audio from the TV back to a home theater receiver and listen to your TV's audio through your home theater audio system instead of the TV's speakers without having to connect a second cable between the TV and home theater system.
  • ATSC: ATSC stands for Advanced Television Standards Committee. This organization is charged with organizing specifications and requirements for High Definition and Digital Television performance and broadcast standards. 

    As a result of the ATSC's partnership with the FCC, all HDTVs manufactured for the U.S. market that include built-in tuners, have to adhere to the technical requirements of the ATSC, as approved by the FCC. As a result, HDTV tuners are referred to as ATSC tuners.
     
  • AV Receiver: The AV receiver is the heart of a home theater system and provides most, if not all, the inputs and outputs that you connect everything, including your television, into. An AV Receiver provides a way of centralizing your home theater system.
  • AV: Audio Video. Equipment and applications that deal with sound and sight.
  • AWG:  AWG stands for American Wire Gauge. It is the thickness of the wire inside the cable. The lower number AWG denotes thicker wiring and therefore a thicker cable overall. 
  • Accelerated Graphics Port: An AGP is an interface specification that enables 3-D graphics to display quickly on ordinary personal computers.
  • Access Point:  An access point provides wireless access to a network. Devices connected to an access point can communicate with other devices on the network. They may also connect to the internet if the access point is linked to an internet connection.
  • Active X Active X is a Microsoft-based technology that was used to link desktop applications to the world wide web. Using Active X development tools, software developers an create interactive web content for their applications.

    Examples of these, are being able to see Word and Excel documents that are being viewed directly in your web browsers.
  • Afocal: Using a camera with its lens attached to take a picture though a telescope's eyepiece.
  • Ambient Light: Any light in the viewing room created by a source other than the projector or screen.
  • Amperage:  A measure of electrical current flow, also called amps for short. It literally equates to the number of electrons in a conductor flowing past a certain point in a given amount of time.
  • Analog (Digital Imaging): Continuously varying information that represents an infinite number of values. Analog data is usually sampled in a discrete, finite number of steps before it is turned into digital data.
  • Analog Television: Analog Television refers to a video display device that receives and displays broadcast television signals that are transmitted utilizing technology that is similar to that used in standard radio transmissions. In fact, the video signal of analog television is transmitted in AM, while the audio is transmitted in FM.

    Analog TV transmissions are subject to interference, such as ghosting and snow, depending on the distance and geographical location of the TV receiving the signal.

    In addition, all analog television signals are transmitted in an interlaced format, in which all the odd lines in the image are transmitted first, then all even lines. These are referred to as fields. Two fields make up one frame of video image.
     
  • Android:  Andoid is Google's mobile operating system. It is used by several smartphones manufacturers like Samsung, LG, Motorola and more.
  • Aperature: The size of the opening that lets light into a camera lens, which can usually be adjusted and changed. In a telescope, the aperture is usually fixed, and is defined by the size of the primary mirror or objective lens.
  • Apple:  Apple is a company that manufactures Macintosh computers, such as the iMac, MacPro, Mac mini, Macbook, Macbook Pro and Macbook Air. They are also known for their mobile devices, such as the iPad, iPod and iPhone.
  • Application:  An application, or application program, is a software program that runs on your computer. Be it a windows-based or apple-based computer, the term "application" remains the same. Web browsers, e-mail programs, word processors, games, and utilities are all applications.
  • Artifacts (Digital Imaging): Artificial, spurious defects in an image that were not part of the original image or data.
  • Aspect Ratio: Aspect Ratio represents the horizontal width of a television or projection screen in relation to it its vertical height. For example, a traditional analog television has a screen aspect ratio of 4x3, which means that for every 4 units in horizontal screen width, there are 3 units of vertical screen height. HDTV's have a an aspect ratio of 16x9, which means that for every sixteen units in horizontal

    In cinematic terms, these ratios are expressed in the following manner: 4x3 is referred to as a 1.33:1 aspect ratio (1.33 units of horizontal width against 1 unit of vertical height) and 16x9 is expressed as a 1.78:1 aspect ratio (1.78:1 units of horizontal width against 1 unit of vertical height).
     
  • aptX: The aptX audio codec is a proprietary audio codec compression algorithm, which allows the real-time streaming of high quality stereo audio over a Bluetooth A2DP connection between a source device and the accessory device.
     
    aptX technology must be incorporated in both the source and the accessory device for it to have any effect. Full backwards compatibility however allows audio streaming even when one of the devices is not aptX compatible, though in this case, the connection won't benefit from the technology.
     
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  • Balanced Audio:  In audio, the opposite of Unbalanced. Balanced refers to a type of AC electrical signal having two "legs" independent of ground. One is generally considered positive (+) and the other negative (-) in voltage and current flow with respect to ground. XLR cables and TRS 1/4 inch cables are designed to transmit balanced audio from one balanced device to another.
  • Bandwidth Bandwidth refers to how much data you can send through a network or modem connection. It is usually measured in bits per second, or "bps".
  • Bayer Array: A CCD or CMOS sensor that has an individual red, green or blue filter over each pixel to synthesize color information from a grayscale sensor. The "Bayer" pattern is also called a Color Filter Array (CFA). It is named after Bryce E. Bayer, the Kodak engineer who invented it. The colored filters are arranged so that out of each four-pixel group, two will be green, one red, and one blue. Bayer found that because human perception was more sensitive to luminance (brightness) information in the green portion of the spectrum, increasing luminance resolution by using more green pixels meant more perceived sharpness in the final image. Color for each individual pixel is created by examining the color of the pixels around it and then processing this information through a sophisticated mathematical algorithm.
  • Black Point: Describes the number of steps of tonal resolution, or brightness levels, that the dynamic range is divided into when it is quantized by the Analog to Digital converter. Bit depth is specified in base 2 notation. Eight bits is 28 or 2 raised to the 8th power. Eight bits equals 256 steps or levels of information. Twelve bits is 212 and equals 4096 levels. Sixteen bits is is 216 and equals 65,536 levels.
  • Blu-ray Region Code: Blu-ray disc are region coded in a similar fashion to a system used to region code DVDs.
    However, instead of eight official regions used for coding DVDs, for Blu-ray Discs, there are only three regions, designated as follows:

    Region A: U.S., Japan, Latin America, East Asia (except China).
    Region B: Europe, Africa, Australia, New Zealand
    Region C: China, Russia, India, remaining countries.
     
    However, despite the provisions for Blu-ray Disc region coding, many Blu-ray Discs are released without region coding. In this case, then you may be able to play a non-region coded disc that is released in another area of the World.
     
  • Blu-ray:  Blu-ray is an optical disc format such as CD and DVD. It was developed for recording and playing back high-definition (HD) video and for storing large amounts of data. While a CD can hold 700 MB of data and a basic DVD can hold 4.7 GB of data, a single Blu-ray disc can hold up to 25 GB of data. Even a double sided, dual layer DVD (which are not common) can only hold 17 GB of data. Dual-layer Blu-ray discs will be able to store 50 GB of data. That is equivalent to 4 hours of HDTV.
  • Bluetooth:  This wireless technology enables communication between Bluetooth-compatible devices. It is used for short-range connections between desktop and laptop computers, smartphones, printers, headphones, and any bluetooth enabled device.
     
  • Bridge:   In computer networking, a bridge serves the same purpose. It connects two or more local area networks (LANs) together.
  • Brightness Value: (Gray Level, Gray Value, Pixel Value, Digital Number) - The brightness of a pixel described as a number. Brightness levels range from 0 for black to 255 for white in an 8-bit image. They can range from 0 to 4095 for a 12-bit image, and 0 to 65,535 for a 16-bit image.
  • Brightness: The attribute of visual perception in accordance with which an area appears to emit more or less light. (Luminance is the recommended name for the photo-electric quantity which has also been called brightness.) Brightness is measured in lumens on a projector.
  • Broadband:  This refers to high-speed data transmission in which a single cable can carry a large amount of data at once. The most common types of Internet broadband connections are cable modems (which use the same connection as cable TV) and DSL modems (which use your existing phone line).
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  • CCD: Charged Coupled Device. A light-sensitive solid-state silicon sensor used in digital cameras to record light intensities.
  • CD: CD stands for Compact Disc. Compact Disc refers to both the disc and the digital audio playback format developed by Philips and Sony in which audio is digitally encoded, similar to the way computer data is encoded, into pits on a disc. The encoding system used in the CD format is a mathematical representation of the music that is recorded. The CD was introduced in 1982 and is still in use. However, disc-less methods of listening to music, such as streaming or downloading content from the internet and playing it back on devices, such as the iPod, iPhones, and Android devices, have eclipsed the CD as the primary way of listening to music for most consumers.
  • CEC: Consumer Electronics Control. An HDMI feature enabling control of up to 15 CEC-enabled devices that are connected through HDMI by using one of their remote controls.
  • CFA: Color Filter Array, A CFA image is a monochrome (black and white and grayscale) image containing data from the Bayer array in the CCD or CMOS sensor in the DSLR camera that has not yet been interpolated into color. It presents the data from each individual filter, which has a red, green or blue color filter over it, as a grayscale tone with a brightness value.
  • CMS: Color Management System, is a way of trying to keep colors consistent across a range of input, display and output devices by the use of software.
     

  • Cable Modem:  A cable modem is used to connect to the internet and is much faster than a dial-up modem. Cable modems can support rates up to 30Mbps.
  • Cache:  A cache stores recently-used information in a place where it can be accessed extremely fast. 

    Web browsers like Internet Explorer uses a cache to store the pages, and URLs of recently visited websites on your hard drive. This makes it faster to load the second time you attempt to access that site.
  • Calibrate: To remove unwanted fixed signals (such as thermal current and bias), and to correct signal modifications (such as vignetting) so that the raw image accurately represents the intensity of light incident on the sensor during the exposure. 
  • Card Reader:  Card reader is the generic term for an input device that reads flash memory cards. It can be a standalone device that connects to a computer via USB or it may be integrated into a computer, printer, or multifunction device. In fact, most multifunction printer/scanner/copiers now have built-in card readers.
     
    Most card readers accept multiple memory card formats, including compact flash (CF), secure digital (SD), and Sony's Memory Stick. Some card readers accept various other formats such as XD, SmartMedia, Microdrive, and Memory Stick Pro Duo cards.
     
  • Cat5e/6: Category 5 enhanced / 6 cable. A 8-count twisted pair cable for carrying signals. Also known as ethernet or networking cables,
  • Character:  A character is any letter, number, space, punctuation mark, or symbol that can be typed on a computer. The word "computer," for example, consists of eight characters. The phrase "Hi there." takes up nine characters. Each character requires one byte of space, so "computer" takes up 8 bytes. 
  • Charge: In digital imaging, the charge created by electrons generated by photons by the photoelectric effect that are stored in a pixel's potential well.
  • Chipset:  A chipset describes the architecture of an integrated circuit. This includes the layout of the circuitry, the components used within the circuit, and the functionality of the circuit board. For example, the chipset of a modem card is much different than the chipset of a computer's CPU.
  • Clean Install:  A clean install is an operating system (OS) installation that overwrites all other content on the hard disk. Unlike a typical OS upgrade, a clean install removes the current operating system and user files during the installation process. When a clean install finishes, the hard disk only contains the new operating system, similar to a computer that is used for the first time.
     
    Both Windows and Mac OS X allow you to perform a clean install when upgrading your operating system. The installer will give you the choice between a standard upgrade (typically the default option) and a clean installation near the beginning of the installation process. Windows 7 also lets you format and partition your installation disk if you select a clean install. In Mac OS X, you can use the Disk Utility program to format or partition your drive before you perform the clean install.
     
    Important: Since a clean install wipes out all data on the primary hard disk, it is crucial to back up your data before performing the installation. While it is wise to make sure you have a recent backup of your data before any OS upgrade, it is extremely important when performing a clean install. Backing up your data to an external hard drive or another computer are both good options. It is also smart to check your backup and make sure it contains all the files you need so you do not accidentally lose any files.
     
  • Codec:  The name "codec" is short for "coder-decoder," which is pretty much what a codec does. Most audio and video formats use some sort of compression so that they don't take up a ridiculous amount of disk space. Audio and video files are compressed with a certain codec when they are saved and then decompressed by the codec when they are played back. Common codecs include MPEG and AVI for video files and WAV and AIFF for audio files. Codecs can also be used to compress streaming media (live audio and video) which makes it possible to broadcast a live audio or video clip over a broadband Internet connection.
  • Color Depth: The number of steps or levels of tone that each primary color of the total dynamic range is divided into. In 24-bit color, 8 bits of color depth are assigned to each color channel of red, green and blue is represented by 256 steps. This yields more than 16 million total colors (256 * 256 * 256 = 16,777,216).
  • Color Gamut: A unique range of colors that a device can capture or represent.
  • Command Prompt:  A command prompt is used in a text-based or "command-line" interface, such as a Unix terminal or a DOS shell. It is a symbol or series of characters at the beginning of a line that indicates the system is ready to receive input. It other words, it prompts the user for a command.
  • Composite Video: A Composite Video Connection is a connection in which both the Color and B/W portions of the video signal are transferred together. The actual physical connection is referred to as an RCA video connection cable and is usually yellow at the tips.

    This connection is the oldest and most common video connection that is still in use. It can still find be found on many video source components and display device, including VCRs, camcorders, DVD players, Cable/Satellite boxes, video projectors, and most TVs.
     
  • Continuous Power: Continuous Power refers to the ability of a receiver or amplifier to output its full power continuously. In other words, just because your receiver/amplifier may be listed as being able to output 100WPC, doesn't mean it can do so for any significant length of time. Always make sure that, when you check for Specifications, that the WPC output is measured in RMS terms. This means that the listed power output is a sustained output at a specific volume level.
  • Contrast Ratio: Contrast ratio is the difference between the brightest whites and the blackest blacks that a television or video projector can display. High contrast ratios deliver whiter whites and blacker blacks and a greater degree of gray values in between. If the contrast ratio is low, even if the image is bright, your image will look washed out. Beware of outrageous contrast ratio numbers based on "Dynamic" or "On/Off" numbers. Look for contrast ratio numbers that refer to "Native" or "ANSI" numbers. 
  • Control Panel:  Control Panel is a feature of the Windows operating system that allows the user to modify system settings and controls. It includes several small applications, or control panels, that can be used to view and change hardware or software settings. Some examples of hardware control panels are Display, Keyboard, and Mouse settings. Software control panels include Date and Time, Power Options, Fonts, and Administrative Tools.
  • Crosstalk: A phenomenon by which a signal transmitted on one circuit or channel creates an undesired effect on another circuit. Generally rare in modern digital wireless phone systems but not entirely eliminated.
     
    Stereo crosstalk for example is one of the parameters of audio quality we test when reviewing mobile phones. The crosstalk measurement is made to determine the amount of signal leaking across from one channel to another or - in purely non-technical terms - it measures how good the stereo is.
     
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  • DDC: Display Data Channel. A collection of protocols for digital communication between a computer display and a graphics adapter that enable the display to communicate its supported display modes to the adapter and that enable the computer host to adjust monitor parameters, such as brightness and contrast.
  • DHCP:  Stands for "Dynamic Host Configuration Protocol." A network server uses this protocol to dynamically assign IP addresses to networked computers. The DHCP server waits for a computer to connect to it, then assigns it an IP address from a master list stored on the server. DHCP helps in setting up large networks, since IP addresses don't have to be manually assigned to each computer on the network. Because of the slick automation involved with DHCP, it is the most commonly used networking protocol.
  • DLP: A video projection technology, developed by Texas Instruments, that utilizes a chip, referred to as a DMD (Digital Micromirror Device). In essence, every pixel on a DMD chip is a reflective mirror.

    The video image is displayed on the DMD chip. The micromirrors on the chip (remember: each micromirror represents one pixel) then tilt very rapidly as the image changes.

    This process produces the grayscale foundation for the image. Then, color is added as light passes through a high-speed color wheel and is reflected off of the micromirrors on the DLP chip as they rapidly tilt towards or away from the light source. The degree of tilt of each micromirror coupled with the rapidly spinning color wheel determines the color structure of the projected image. As the amplified light bounces off the micromirrors, it is sent through the lens and can be projected on a large screen.
     
  • DNS:  Stands for "Domain Name System." The reason the Domain Name System is used is because Web sites are actually located by their IP addresses. For example, when you type in "http://www.adobe.com," the computer doesn't immediately know that it should look for Adobe's Web site. Instead, it sends a request to the nearest DNS server, which finds the correct IP address for "adobe.com." Your computer then attempts to connect to the server with that IP number.
  • DPI: Dots Per Inch. A measure of resolution that refers to the number of dots a printer can print in an inch of output. Higher resolution means more dots per inch. Often mistakenly used for PPI, or pixels per inch. It more correctly applies to output devices that print with dots, such as inkjet printers.
  • DPI:  Stands for "Dots Per Inch." DPI is used to measure the resolution of an image both on screen and in print. As the name suggests, the DPI measures how many dots fit into a linear inch. Therefore, the higher the DPI, the more detail can be shown in an image.

    In terms of gaming, DPI is a measurement of how sensitive a mouse is. The higher the DPI, the farther the curson on your screen will move when the mouse is moved. A mouse with a higher DPI setting detects and reacts to smaller movements.
  • DSL:  Stands for "Digital Subscriber Line." It is a medium for transferring data over regular phone lines and can be used to connect to the Internet. However, like a cable modem, a DSL circuit is much faster than a regular phone connection, even though the wires it uses are copper like a typical phone line.
  • DSLR: Digital Single Lens Reflex. A camera that uses a mirror to intercept the light from the camera's lens and send it to a focusing screen for inspection by the photographer's eye. The reflex mirror swings up and out of the way when the picture is taken, allowing the light to reach the digital sensor.
  • DTS: DTS is a 5.1 channel encoding and decoding system similar to Dolby Digital 5.1, but DTS uses less compression in the encoding process. As a result, many feel that DTS has a better result on the listening end.

    In addition, while Dolby Digital is mainly intended for the Movie Soundtrack experience, DTS is also used in the mixing and reproduction of musical performances.
     
  • DVD Recorder: A DVD recorder typically refers to a standalone unit that resembles and functions very much like a VCR, but records onto a DVD disc, rather than a video tape. All DVD recorders can record from any analog video source (most can also record video from digital camcorders via firewire, iLink, IEEE1394, DV connection).
  • DVD Region Code: Region Codes are a DVD coding system enforced by the movie industry that is intended to preserve movie distribution rights and agreements.

    DVD players and DVDs are labeled for operation on within a specific geographical region in the world. For example, the U.S. is in region 1. All DVD players sold in the U.S. are made to region 1 specs. Region 1 players can only play region 1 discs.
     
  • DVD: DVD stands for Digital Versatile Disc. DVDs can be used for storing video, audio, still image, or computer data.
  • DVI: Stands for "Digital Video Interface." DVI is a video connection standard created by the Digital Display Working Group (DDWG).  DVI is capable of supporting analog and digital signals depending on the devices themselves.
    There are three types of DVI connections:
    1) DVI-A (for analog)
    2) DVI-D (for digital)
    3) DVI-I (integrated, for both analog and digital).
    The digital video interface supports high bandwidth signals, over 160 MHz, which means it can be used for high resolution displays such as UXGA and HDTV. You may find DVI ports on video cards in computers as well as on high-end televisions.
     
  • DVR:  Stands for "Digital Video Recorder." A DVR is basically a VCR that uses a hard drive instead of video tapes. It can be used to record, save, and play back television programs. Unlike a VCR, however, a DVR can also pause live TV by recording the current show in real time. The user can choose to fast forward (often during commercials) to return to live television.
     
    Most satellite and cable TV companies offer a DVR as an option with their digital television packages. Since cable boxes already provide program listings through some kind of TV guide interface, most DVRs allow users to use the guide to schedule recordings. For example, a user can use the remote to search through the guide's program listings for the current week and select the shows he would like to record.
     
  • Dashboard:  Dashboard is a user-interface feature Apple introduced with the release of Mac OS X 10.4 Tiger. It allows access to all kinds of "widgets" that show the time, weather, stock prices, phone numbers, and other useful data. With the Tiger operating system, Apple included widgets that do all these things, plus a calculator, language translator, dictionary, address book, calendar, unit converter, and iTunes controller. Besides the bundled widgets, there are also hundreds of other widgets available from third parties that allow users to play games, check traffic conditions, and view sports scores, just to name a few.
  • Data Management:  Data management refers to the way individuals, companies, and organizations manage computer data. It includes micro applications, such as data architecture and design, as well as macro applications, including data storage, access, and security. While computer data may be intangible, it can also be valuable. Therefore, it is important for all users to consider how they manage their data. This may involve taking steps such as backing up important files and encrypting personal information.
  • Data Transfer Rate:  The data transfer rate is commonly used to measure how fast data is transferred from one location to another. For example, a hard drive may have a maximum data transfer rate of 480 Mbps, while your ISP may offer an Internet connection with a maximum data transfer rate of only 1.5 Mbps.
  • Data:  Computer data is information processed or stored by a computer. This information may be in the form of text documents, images, audio clips, software programs, or other types of data. Computer data may be processed by the computer's CPU and is stored in files and folders on the computer's hard disk.
  • Dead Pixel:  An individual pixel in a sensor that does not respond to light and appears as black in an image.
  • Decibels: Our ears detect changes in volume in a non-linear fashion. A decibel is a logarithmic scale of loudness. A difference of 1 decibel is perceived as a minimum change in volume, 3 db is a moderate change, and 10 decibels is perceived by the listener as a doubling of volume. Decibels are designated by the letters: db.
  • Default:  This term is used to describe a preset value for some option in a computer program. It is the value used when a setting has not been specified by the user.
  • Desktop Computer:  A desktop computer is a computer system designed to be used at a table or desk. Some desktop computers have a separate monitor and system unit, while others are "all-in-one" models, in which the monitor is built into the computer. All-in-one computers are designed to sit on a desktop, while system units are usually placed on the ground. Both types of desktop computers include a keyboard and mouse as input devices.
  • Desktop:  Your computer's desktop is much like a physical desktop. Your computer's desktop serves this purpose - to give you easy access to items on your hard drive. It is common to store frequently used files, folders, and programs on your desktop. This allows you to access the items quickly instead of digging through the directories on your hard drive each time you want to open them.
  • Digital Camera:  A digital camera is an electronic device that captures images in a digital format. It works in a similar way to a film-based camera, but uses a sensor called a CCD to record images rather than a strip of film. Once an image or video is captured by the CCD, it is saved to a memory card, such as an SD card. Images and videos saved to the memory card can be imported to a computer using a standard USB cable.
  • Digital Coaxial Connection: A digital coaxial connection refers to a wired connection that is used for transferring digital audio signals (such as PCM, Dolby Digital, and DTS) from a source device, such as CD or DVD player and an AV receiver or Surround Sound Preamp/Processor. Digital Coaxial Connections use RCA-style connection plugs.
     
  • Digital Optical Connection: A digital optical connection refers to a fiber-optic connection that is used for transferring digital audio signals (such as PCM, Dolby Digital, and DTS) from a source device, such as CD or DVD player and an AV receiver or Surround Sound Preamp/Processor. Also known as Toslink.
  • Direct 3D:  Direct3D is an application program interface developed by Microsoft that provides a set of commands and functions for manipulating 3D objects. By using Direct3D commands, software developers can take advantage of many prewritten functions. This allows programmers to write significantly less code than if they had to write all the functions from scratch. Direct3D makes it relatively easy to manage three-dimensional objects, including lighting and shadows as well.
  • Dolby Digital EX: Dolby Digital EX is based on the technology already developed for Dolby Digital 5.1. This process adds a third surround channel that is placed directly behind the listener.
  • Dolby Pro Logic IIz: Dolby Pro Logic IIz processing is an enhancement that extends surround sound vertically. Dolby Pro Logic IIz offers the option of adding two more front speakers that are placed above the left and right main speakers. This feature adds a "vertical" or overhead component to the surround sound field (great for rain, helicopter, plane flyover effects). Dolby Prologic IIz can be added to either a 5.1 channel or 7.1 channel setup.
  • Dolby True HD: Dolby TrueHD is a high definition digital-based surround sound format that supports up to 8-channels of surround decoding and is bit-for-bit identical to a studio master recording. Dolby TrueHD is one of the several audio formats designed and employed by Blu-ray Disc and HD-DVD technologies. Dolby TrueHD is compatible with the audio portion of the HDMI interface.
  • Domain:  A domain contains a group of computers that can be accessed and administered with a common set of rules. For example, a company may require all local computers to be networked within the same domain so that each computer can be seen from other computers within the domain or located from a central server. Setting up a domain may also block outside traffic from accessing computers within the network, which adds an extra level of security.
  • Dongle:  This is a hardware device that plugs into the USB port or PCMCIA of a computer. Mainly used to connect a device for networking purposes.  Can be used to identify a device such as a Bluetooth transceiver, Wireless adapter, or USB to Ethernet adapter to the computer.
  • Download:  This is the process in which data is sent to your computer. Whenever you receive information from the Internet, you are downloading it to your computer.
  • Driver:  This term usually refers to the person behind the wheel of a moving car. In the computer world, however, a driver is a small file that helps the computer communicate with a certain hardware device. It contains information the computer needs to recognize and control the device.
  • Dual Band IR: Dual band extenders work on both frequencies, making them work with virtually everything. This is a good option, especially when there is any question about what frequency your device uses.
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  • EDID: Extended Display Identification Data. A data structure provided by a digital display to describe its capabilities to a video source.
  • Email:  E-mail is part of the standard TCP/IP set of protocols. Sending messages is typically done by SMTP (Simple Mail Transfer Protocol) and receiving messages is handled by POP3 (Post Office Protocol 3), or IMAP (Internet Message Access Protocol). IMAP is the newer protocol, allowing you to view and sort messages on the mail server, without downloading them to your hard drive.
  • End User:  An end user is the person that a software program or hardware device is designed for. The term is based on the idea that the "end goal" of a software or hardware product is to be useful to the consumer. The end user can be contrasted with the developers or programmers of the product. End users are also in a separate group from the installers or administrators of the product.
  • Ethernet Switch: A switch is used to network multiple computers together. Switches made for the consumer market are typically small, flat boxes with 4 to 8 Ethernet ports. These ports can connect to computers, cable or DSL modems, and other switches. High-end switches can have more than 50 ports and often are rack mounted.
  • Ethernet:  Ethernet is the most common type of connection computers use in a local area network (LAN). An Ethernet port looks much like a regular phone jack, but it is slightly wider. This port can be used to connect your computer to another computer, a local network, or an external DSL or cable modem.

    Two widely-used forms of Ethernet are 10BaseT and 100BaseT. In a 10BaseT Ethernet connection, data transfer speeds can reach 10 mbps (megabits per second) through a copper cable. In a 100BaseT Ethernet connection, transfer speeds can get up to 100 mbps. There is also a new technology called "Gigabit" Ethernet, where data transfer rates peak at 1000 mbps.
     
  • External Hard Drive:  An external hard drive is a portable storage device that can be attached to a computer through a USB or FireWire connection, or wirelessly. External hard drives typically have high storage capacities and are often used to back up computers or serve as a network drive. 
  • Extruder: In 3D printing, it is also known as the the 3D printer head. It is responsible for raw material melting and forming it into a continuous profile.
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  • FAT32:  This strange term refers to the way Windows stores data on your hard drive. "FAT" stands for "File Allocation Table," which keeps track of all your files and helps the computer locate them on the disk. Even if a file gets fragmented (split up into various areas on the disk), the file allocation table still can keep track of it. FAT32 is an improvement to the original FAT system, since it uses more bits to identify each cluster on the disk. This helps the computer locate files easier and allows for smaller clusters, which improves the efficiency of your hard disk. FAT32 supports up to 2 terabytes of hard disk storage. 
  • FOV: Field of view is the ‚Äčamount of a scene that is captured by a given focal-length lens. Wide-angle, short-focal length lenses capture a wide field of view. Telephoto lenses and telescopes capture a very narrow field of view. The field of view is usually specified as an angle that depends on the size of the sensor. For example, a lens or telescope of 500mm focal length will cover a field of view of 4 degrees, 17 arc minutes, 43 arc seconds by 2 degrees 51 arc minutes, 51 arc seconds with a Canon 20Da DSLR camera sensor that is 22.5 x 15mm.
  • Fiber Optic Cable:  This is a cable made up of super-thin filaments of glass or other transparent materials that can carry beams of light. Because a fiber-optic cable is light-based, data can be sent through it at the speed of light. Using a laser transmitter that encodes frequency signals into pulses of light, ones and zeros are sent through the cable. The receiving end of the transmission translates the light signals back into data which can be read by a computer.

    Because fiber optics are based entirely on beams of light, they are less susceptible to noise and interference than other data-transfer mediums such as copper wires or telephone lines. However, the cables are fragile and are usually placed underground, which makes them difficult and expensive to install. Some fiber-optic cables are installed above ground, but if they break, they often need to be completely replaced, which is not cheap. While copper wires can be spliced and mended as many times as needed, it is much harder to fix glass fiber-optic cables.
     
  • File Extension:  A file extension is the last part of a filename, after the dot (e.g. ".pdf"). Most file extensions are three characters long, but they can be shorter or longer as well. File extensions are used to define the file type of each file. The operating system uses this information to select which application will open the file and choose the appropriate icon for the file.
  • File Format: The structure of a specific type of computer file. Different file formats are associated with different file types and programs. For example, JPEG and TIFF file formats are associated with image files. Their codes are JPG and TIF respectively. Files of a particular format are given a specific file extension in the form of a three letter code. 
  • Filename: A filename is a text string that identifies a file. Every file stored on a computer's hard disk has a filename that helps identify the file within a given folder. Therefore, each file within a specific folder must have a different filename, while files in different folders can have the same name.
  • Filter: 1.) A piece of glass or gelatin placed in the optical path that modifies the wavelength or light that ultimately reaches the sensor. An example would be a hydrogen-alpha filter that only allows the light of the hydrogen-alpha wavelength to pass.

    2.) A piece of software that performs particular algorithms on digital data. An example would be a Gaussian blur filter in Photoshop that blurs an image.
  • Finder: The Finder serves as the primary graphical user interface (GUI) for Macintosh computers. It includes the desktop, icons, a menu bar, and the Dock. The Finder allows users to open windows and manage files and folders. While the Finder is technically a Mac OS X application, it automatically loads at startup and is always running.
  • Firewall: A computer firewall limits the data that can pass through it and protects a networked server or client machine from damage by unauthorized users.

    Firewalls can be either hardware or software-based. A router is a good example of a hardware device that has a built-in firewall.
     
  • Firewire: A standard Firewire connection can transfer data at 400 Mbps, which is roughly 30 times faster than USB 1.1. This blazing speed allows for quick transfers of large video files, which is great for video-editing professionals. If 400 Mbps is still not fast enough, Apple Computer released new PowerMacs with Firewire 800 ports in early 2003. These ports support data transfer rates of 800 Mbps -- twice the speed of the original Firewire standard.

    You may see Firewire referred to by its technical name, IEEE 1394, since it was standardized by the Institute of Electrical and Electronics Engineers. Both terms refer to the same technology. If your computer doesn't have Firewire and you wish it did, fear not. As long as your computer has PCI slots, you can purchase a PCI Firewire card to add Firewire ports to your computer.

    Firewire can be used to connect devices such as digital video cameras, hard drives, audio interfaces, and computers.
     
  • Firmware: Firmware is a software program or set of instructions programmed on a hardware device. It provides the necessary instructions for how the device communicates with the other computer hardware. 
  • Flash Drive: Flash drives have many names - jump drives, thumb drives, pen drives, and USB keychain drives. Regardless of what you call them, they all refer to the same thing, which is a small data storage device that uses flash memory and has a built-in USB connection.
  • Flash: Flash is a multimedia technology used for creating animations and interactive websites. Web developers often use Flash to add dynamic content that is not possible with HTML or other scripting languages. Some examples include splash screen animations, YouTube videos, and interactive song playlists.
  • Focal Length: The distance from the lens or mirror in an optical system and the focal plane where the light is focused.
  • Folder: Folders on your hard drive store files. These files can be documents, programs, scripts, libraries, and any other kind of computer file you can think of. Folders can also store other folders, which may store more files or other folders, and so on.
  • Format: Formatting a disk involves rewriting the directory structure, or file system, of a disk. All disks must be formatted using a supported file system in order to work with a computer. Therefore, it may be necessary to format (or reformat) a disk if it is not formatted for the computer you are using. While the formatting process technically does not erase the files on the disk, it does make them inaccessible, since they are no longer part of the directory structure. Therefore, make sure you don't format or reformat a disk that contains important data.
  • Frame: 1.) Used as a noun, a frame is an image or an exposure. Derived from the days of film where images were taken on a roll of film and each individual image was called a frame. In digital astrophotograhy, you can have light frames, dark frames, bias frames and flat-field frames. 

     2.) Used as a verb, to frame means to compose the subject inside of the viewfinder. For example, you want to "frame" the Orion Nebula so that none of the faint outer nebulosity gets cut off.
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  • GPS: Stands for "Global Positioning System." GPS is a satellite navigation system used to determine ground position and velocity (location, speed, and direction). Though it was created and originally used by the U.S. military, GPS is now available to the general public all over the world. GPS navigation systems are currently installed in a number of luxury cars, complete with an LCD map that shows the driver exactly where in the world he is. 
  • GPU: Stands for "Graphics Processing Unit." Like the CPU (Central Processing Unit), it is a single-chip processor. However, the GPU is used primarily for computing 3D functions. This includes things such as lighting effects, object transformations, and 3D motion. Because these types of calculations are rather taxing on the CPU, the GPU can help the computer run more efficiently.
  • GUI: Stands for "Graphical User Interface," and is pronounced "gooey." It refers to the graphical interface of a computer that allows users to click and drag objects with a mouse instead of entering text at a command line. Two of the most popular operating systems, Windows and the Mac OS, are GUI-based. 
  • Gain: Gain defines how many electrons are represented by each Analog to Digital Unit (ADU). A gain of 4 means that the A/D converter has digitized the signal so that each ADU corresponds to 4 electrons. DSLR cameras can change ISO by changing the gain.
  • Gamma Correction: Gamma correction is used to alter the output levels of a display. Since the standard input signal (or voltage level) is not high enough to create a bright picture, gamma correction is used to boost the brightness and contrast of the display. PCs typically use a gamma setting of 2.2, while Macs have a default gamma setting of 1.8. Some systems include a display utility that can be used to apply custom gamma settings.
  • Gamma: In photography, gamma refers to the midtone contrast of an image. Technically, gamma refers to the relationship between input voltage and output intensity, where gamma is the exponent in a power-law relationship between input values and output displayed brightness, such as in a computer monitor.
  • Gamut: The range of colors that can be detected, recorded or displayed by an imaging device. Each device has a unique gamut.
  • Ghosting: A shadow or weak secondary image as seen on a monitor or display which is created by multiple path broadcast transmission errors.
  • Gigabyte: A gigabyte is 2 to the 30th power, or 1,073,741,824 bytes.

    It can be estimated as 10 to the 9th power, or one billion (1,000,000,000) bytes. A gigabyte is 1,024 megabytes and precedes the terabyte unit of measurement. Hard drive sizes are typically measured in gigabytes, such as a 160GB or 250GB drive. The term gigabyte is often often abbreviated as simply a "gig" in speech.
     
  • Graphic Tablet: A graphics tablet or digitizer is a computer input device that enables a user to hand-draw images, animations and graphics, similar to the way a person draws images with a pencil and paper. These tablets may also be used to capture data or handwritten signatures. It can also be used to trace an image from a piece of paper which is taped or otherwise secured to the surface. Capturing data in this way, by tracing or entering the corners of linear poly-lines or shapes, is called digitizing.
  • Graphics: Computer graphics are images displayed on a computer screen. They can be either two or three-dimensional. Two-dimensional graphics come in raster or vector formats.
     
    Raster graphics are the most common type of computer graphic and are used for icons, photos, and other basic images. Vector graphics are used for drawings, logos, and other scalable objects. 3D graphics are made up of polygons and can be created with CAD and 3D modeling programs. They are most commonly seen in video games and 3D animations.
     
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  • HD-DVD: HD-DVD is one of two major High Definition DVD formats (the other format is Blu-ray) that were vying to replace the DVD standard in the U.S. market. HD-DVD was supported on the hardware side by Toshiba, NEC, Sanyo, Thomson (Note: Thomson also supports Blu-ray). On the software side, HD-DVD was supported by New Line Cinema, Paramount Pictures, and Universal Pictures. Microsoft also aded its support for HD-DVD. However, in February 2008, HD-DVD was discontinued. As a result HD-DVD players and discs are no longer being manufactured, but there is still a viable secondary market.
  • HD: High Definition. A device capable of generating or displaying a signal with a resolution of at least 720 vertical lines (i.e., 720p). Another accepted definition is any signal containing at least one million pixels of video data in a single frame (vertical resolution x horizontal resolution).
  • HDBaseT: A technology that empowers plug-and-play digital connectivity between HD video sources and remote displays. HDBaseT delivers the 5PlayTM feature (A feature set of HDBaseT that enables delivering video, audio, Ethernet, control signals, and power over a single 100m / 328ft CAT5e / 6 cable) set over a single 100m cat5e/6 cable.
  • HDCP: HDCP stands for High-bandwidth Digital Content Protection. HDCP is a copy-protection process that can allow for specific restrictions on the use of high definition video content, such as the inability to record programs through HDMI connections. HDCP encoding is commonly used on components, such as HDTVs, Blu-ray Disc Players, and Upscaling DVD Players, that have DVI (Digital Visual Interface) or HDMI (High Definition Multimedia Interface) connections.
  • HDD: HDD is short for "hard disk drive." An HDD is a storage device used to store data. Unlike RAM, which requires electrical power to maintain its state, a hard disk drive stores data magnetically. Therefore, it retains its data when the power source is turned off or disconnected.

    Important: The term "hard disk drive" may be used synonymously with the terms "hard drive" and "hard disk." Technically, an HDD and a hard drive refer to the same thing, while a hard disk refers to the actual magnetic platter inside the drive case.
     
  • HDMI: Stands for "High-Definition Multimedia Interface." HDMI is a digital interface for transmitting audio and video data in a single cable. It is supported by most HDTVs and related components, such as DVD and Blu-ray players, cable boxes, and video game systems.
     
    While other types of A/V connections require separate cables for audio and video data, HDMI carries the audio and video streams together, greatly eliminating cable clutter. For example, a component cable connection requires three cables for video and two for audio, totaling five cables in all. The same information can be transmitted using one HDMI cable.
     
  • HDR: 1.) An image with a larger dynamic range than usual.

    2.) A method of combining different exposures to extend the dynamic range recorded in an image, such as Photoshop CS2's HDR function.
     
  • HDTV: Stands for "High Definition Television." HDTV is a high-quality video standard developed to replace older video formats often referred to as SDTV (standard definition television). While HDTV's video quality is one of the most noticeable improvements over SDTV, HDTV includes a number of other important improvements as well.
  • HTIB: A Home Theater-In-A-Box is a system that contains most (or all) of the components in one package needed for a basic Home Theater, including all speakers, a surround sound receiver section, and, many times a DVD/CD player, or even a Blu-ray Disc player. If you are getting into home theater for the very first time and don't know what get and how to set everything, a Home Theater-In-A-Box may be a great way to get started.
  • HTPC: A PC (personal computer) that you can connect to your TV or home theater system to play back audio and video content either stored on the PC or downloaded or streamed from the internet. An HTPC can also come equipped with DVD and Blu-ray disc playback capabilities, as well as DVR functions
  • Hard Disk: When you save data or install programs on your computer, the information is typically written to your hard disk. The hard disk is a spindle of magnetic disks, called platters, that record and store information. Because the data is stored magnetically, information recorded to the hard disk remains intact after you turn your computer off. This is an important distinction between the hard disk and RAM, or memory, which is reset when the computer's power is turned off.
  • Hard Drive: The hard drive is what stores all your data. It houses the hard disk, where all your files and folders are physically located. A typical hard drive is only slightly larger than your hand, yet can hold over 100 GB of data. The data is stored on a stack of disks that are mounted inside a solid encasement. These disks spin extremely fast (typically at either 5400 or 7200 RPM) so that data can be accessed immediately from anywhere on the drive. The data is stored on the hard drive magnetically, so it stays on the drive even after the power supply is turned off.
  • Hardware: Computer hardware refers to the physical parts of a computer and related devices. Internal hardware devices include motherboards, hard drives, and RAM. External hardware devices include monitors, keyboards, mice, printers, and scanners.
  • Hibernate: If you are not going to use your computer for a few hours, it is a good idea to put it to sleep (also known as standby mode) to save power. If you are not going to use the computer for more than a day, it is usually best to turn it off. However, some Windows computer offer an option that combines the benefits of sleep mode and powering down the computer, called "Hibernate."
     
    When you select Hibernate, the computer saves the current state of the system from the computer's RAM to the hard disk, then shuts down. When the computer is restarted, instead of going through the typical boot sequence, the previously saved state is automatically loaded into the RAM. The open windows and running programs from your previous session appear just as they were when the computer entered Hibernate mode. Basically, Hibernate mode acts like Standby mode, except the computer can be completely turned off. This is especially helpful for laptop computers, which will slowly lose their battery charge if they are left in sleep mode.
     
  • Home Theater: The term, Home theater (also referred to as Home Theatre or Home Cinema), is a setup of audio and video equipment in your home that tries to duplicate the movie theater experience.
  • Homepage: This is the starting point or front page of a Web site. This page usually has some sort of table of contents on it and often describes the purpose of the site.
  • Hot Key: A hot key is a key or a combination of keys on a computer keyboard that, when pressed at one time, performs a task (such as starting an application) more quickly than by using a mouse or other input device. Hot keys are sometimes called shortcut keys. Hot keys are supported by many operating system and applications.
  • Hyperlink: A hyperlink is a word, phrase, or image that you can click on to jump to a new document or a new section within the current document. Hyperlinks are found in nearly all Web pages, allowing users to click their way from page to page. Text hyperlinks are often blue and underlined, but don't have to be. When you move the cursor over a hyperlink, whether it is text or an image, the arrow should change to a small hand pointing at the link. When you click it, a new page or place in the current page will open.
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  • IP Address: Also known as an "IP number" or simply an "IP," this is a code made up of numbers separated by three dots that identifies a particular computer on the Internet. Every computer, whether it be a Web server or the computer you're using right now, requires an IP address to connect to the Internet. IP addresses consist of four sets of numbers from 0 to 255, separated by three dots. For example "66.72.98.236" or "216.239.115.148". Your Internet Service Provider (ISP), will assign you either a static IP address (which is always the same) or a dynamic IP address, (which changes every time you log on). ISPs typically assign dial-up users a dynamic IP address each time they sign on because it reduces the number of IP addresses they must register. However, if you connect to the Internet through a network or broadband connection, it is more likely that you have a static IP address.
  • IPv4: IPv4 is the fourth revision of the Internet Protocol and is the most common version used today. It uses 32-bit addresses, which are formatted as "111.111.111.111." Each section may contain a number from 0 to 255, which provides a total of 4,294,967,296 (2^32) possible addresses.
  • IPv6: Pv6, also called IPng (or IP Next Generation), is the next planned version of the IP address system. (IPv5 was an experimental version used primarily for streaming data.) While IPv4 uses 32-bit addresses, IPv6 uses 128-bit addresses, which increases the number of possible addresses by an exponential amount. For example, IPv4 allows 4,294,967,296 addresses to be used (2^32). IPv6 allows for over 340,000,000,000,000,000,000,000,000,000,000,000,000 IP addresses. That should be enough to last awhile.

    Because IPv6 allows for substantially more IP addresses than IPv4, the addresses themselves are more complex. They are typically written in this format:

    hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh:hhhh
     
    Each "hhhh" section consists of a four-digit hexadecimal number, which means each digit can be from 0 to 9 and from A to F. An example IPv6 address may look like this:
     
    F704:0000:0000:0000:3458:79A2:D08B:4320
     
    Because IPv6 addresses are so complex, the new system also adds extra security to computers connected to the Internet. Since there are so may IP address possibilities, it is nearly impossible to guess the IP address of another computer. While most computer systems today support IPv6, the new Internet protocol has yet to be fully implemented. During this transitional process, computers are often assigned both an IPv4 and an IPv6 address. By 2008, the U.S. government has mandated that all government systems use IPv6 addresses, which should help move the transition along.
     
  • ISO: An international standard published by the International Organization for Standardization. In the field of photography, the term ISO is used as a shorthand name for the standard defined by the specification for determining the sensitivity to light of film or a digital camera sensor. In film, a higher ISO number means the film is more sensitive to light. Digital camera sensors really only have one sensitivity to light though. Changing the ISO on a digital camera changes the gain in the camera, seemingly changing the sensitivity.
  • ISP: Stands for "Internet Service Provider." In order to connect to the Internet, you need an ISP. If you use a dial-up modem to connect to your ISP, a point-to-point protocol (PPP) connection is established with another modem on the ISP's end. That modem connects to one of the ISP's routers, which routes you to the Internet "backbone." From there, you can access information from anywhere around the world. DSL and cable modems work the same way, except after you connect the first time, you are always connected.
  • Impedance The resistance and reactance of a conductor or component measured in ohms. The lower the ohm value, the better the quality of the conductor.
  • Inbox: An inbox is the main folder that your incoming mail gets stored in. Whether you check your mail through a webmail interface or use a program like Outlook or Mac OS X Mail, each downloaded message gets stored in your inbox.
  • Inkjet: Inkjet printers are the most common type of consumer printers. The inkjet technology works by spraying very fine drops of ink on a sheet of paper. These droplets are "ionized" which allows them to be directed by magnetic plates in the ink's path. As the paper is fed through the printer, the print head moves back and forth, spraying thousands of these small droplets on the page.
  • Install: Most software programs require that you first install them on your computer before using them. For example, if you buy Microsoft Office, you need to install it on your computer before you can run any of the included programs such as Word or Excel. You can install software from a CD or DVD, an external hard drive, or from a networked computer. You can also install a program or software update from a file downloaded from the Internet.

    Installing a software program writes the necessary data for running the program on your hard drive. Often the installer program will decompress the data included with the installer immediately before writing the information to your hard drive. Software updates, which are typically downloaded from the Internet, work the same way. When you run the update, the installer file decompresses the data and then updates the correct program or operating system.
     
  • Installer: In order to install new software on your computer, you often need to run an installer program. This program unpacks compressed data included with the installer and writes new information to your hard drive. While some installers do not use compressed data, most use some level of compression since it reduces the size of the files included with the installer. This is especially helpful when downloading programs or software updates from the Internet.
  • Interlaced Scan: Interlaced scan refers to a video image that is displayed on a screen by scanning or displaying each line (or row of pixels) that make up the image, in an alternate order. In other words, the image lines (or pixel rows) are scanned down the screen from top to bottom, in an alternate order (lines or rows 1, 3, 5, etc... followed by lines or rows 2, 4, 6). The entire image is displayed every 30th of a second.
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  • Javascript: This is a programming language designed by Sun Microsystems, in conjunction with Netscape that can be integrated into standard HTML pages. While JavaScript is based on the Java syntax, it is a scripting language, and therefore cannot be used to create stand-alone programs. Instead, it is used mainly to create dynamic, interactive Web pages.
  • Jumper: This is a small metal connector that acts as an on/off switch and is used to alter hardware configurations. A jumper is typically made of two wires and a small piece of metal. When the wires are connected by the metal piece, the jumper is turned on, completing the circuit. When the wires are disconnected, the jumper is turned off.
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  • KVM Switch: Stands for "Keyboard, Video, and Mouse switch." As the name implies, a KVM switch allows you to use multiple computers with the same keyboard, video display, and mouse. Now, most of us don't need to use two computers at once. In fact, using one computer at a time can sometimes be a challenge. However, there are situations where using a single keyboard, mouse, and display with multiple machines can be very practical.
  • Kbps: Stands for "Kilobits Per Second." Don't confuse this with Kilobytes per second (which is 8 times more data per second). This term is commonly used in describing data transfer rates. 
  • Keyboard Shortcut: A keyboard shortcut is a key combination that performs a certain command, such as closing a window or saving a file. For example, pressing "Control-S" in a Windows program or "Command-S" on the Mac is the standard shortcut for saving an open document. You can also usually close a window on the Mac by pressing "Command-W" or by pressing "Alt-F4" in Windows. The shortcut for copying data is usually "Control-C" (Windows) or "Command-C" (Mac) and for pasting data, it is "Control-V" (Windows) or "Command-V" (Mac).
  • Keyboard: As the name implies, a keyboard is basically a board of keys. Along with the mouse, the keyboard is one of the primary input devices used with a computer. The keyboard's design comes from the original typewriter keyboards, which arranged letters and numbers in a way that prevented the type-bars from getting jammed when typing quickly. This keyboard layout is known as the QWERTY design, which gets its name from the first six letters across in the upper-left-hand corner of the keyboard.
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  • LAN: Stands for "Local Area Network. A LAN is a computer network limited to a small area such as an office building, university, or even a residential home. Most mid to large-sized businesses today use LANs, which makes it easy for employees to share information. Currently, the most common type of LANs are Ethernet-based and use software from Novell or Oracle. However, with the emergence of wireless networking, wireless LANs have become a popular alternative.
  • LCD Television: An LCD Television is a flat panel television that utilizes the same basic Liquid Crystal Display technology that has been in used for some time in cell phones, camcorder viewfinders, and computer monitors.

    LCD panels are made of two layers of a glass-like material, which are polarized, and are "glued" together. One of the layers is coated with a special polymer that holds the individual liquid crystals. Electric current is then passed through individual crystals, which allow the crystals to pass or block light to create images.
     
  • LCD: Stands for "Liquid Crystal Display." LCDs are super-thin displays that are used in laptop computer screens and flat panel monitors. Smaller LCDs are used in handheld TVs, PDAs, and portable video game devices. The image on an LCD screen is created by sandwiching an electrically reactive substance between two electrodes. This color of this substance can be changed by increasing or reducing the electrical current. Since LCD screens are based on the principle of blocking light (rather than emitting it), they use up much less power than standard CRT (Cathode-Ray Tube) monitors.
  • LED: LED is short for "Light-Emitting Diode." It is a type of electronic light source that is activated by an electrical current. LEDs are highly energy-efficient and last much longer than traditional light bulbs. They can used for indicator lights, clock displays, street lights, and many other applications. LEDs have also begun to replace traditional bulbs as the backlight source in LCD monitors and TVs.
  • LFE: FE stands for: Low Frequency Effects. LFE is represented by extremely low audio frequencies present in DVD or Blu-ray Disc film soundtracks that can only be reproduced by a subwoofer.
  • Laptop: Laptop computers, also known as notebooks, are portable computers that you can take with you and use in different environments. They include a screen, keyboard, and a trackpad or trackball, which serves as the mouse. Because laptops are meant to be used on the go, they have a battery which allows them to operate without being plugged into a power outlet. Laptops also include a power adapter that allows them to use power from an outlet and recharges the battery.
  • Laser Printer: A laser printer is a printer that uses a focused beam or light to transfer text and images onto paper. Though contrary to popular belief, the laser does not actually burn the images onto the paper. Instead, as paper passes through the printer, the laser beam fires at the surface of a cylindrical drum called a photoreceptor. This drum has an electrical charge (typically positive), that is reversed in areas where the laser beam hits it. By reversing the charge in certain areas of the drum, the laser beam can print patterns (such as text and pictures) onto the photoreceptor.
  • Latency: This is the amount of time it takes a packet of data to move across a network connection. When a packet is being sent, there is "latent" time, when the computer that sent the packet waits for confirmation that the packet has been received. Latency and bandwidth are the two factors that determine your network connection speed.
  • Layers: A separate channel from the color channels used to store information in a photo-editing program, such as Photoshop. Layers can be used for color and tonal adjustments without altering the original data in the file until the layer is merged or "flattened" with the other channels. Layers also allow the creation of masks for use in an image.
  • Levels: Individual steps of brightness in an image. The Levels command in Photoshop allows adjustment of an images black and white points and mid-tone gamma in each individual color channel.
  • Li-on: Lithium Ion (Li-on) is a type of rechargeable battery. They are much lighter than earlier battery types and have a longer life cycle.
  • Link: When you are browsing the Web and you see a highlighted and underlined word or phrase on a page, there is a good chance you are looking at a link. By clicking on a link, you can "jump" to a new Web page or a completely different Web site. While text links are typically blue and underlined, they can be any color and don't have to be underlined. Images can also serve as links to other Web pages. When you move the cursor over a link in a Web page, the arrow will turn into a little hand, letting you know that it is a link.
  • Lumen: A unit of measurement of the amount of visible light energy coming from a light source and perceived by the eye. One lumen is the light of one candle power on each square foot of a sphere at a radius of one foot from the light source.
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  • MAC Address: Stands for "Media Access Control Address," and no, it is not related Apple Macintosh computers. A MAC address is a hardware identification number that uniquely identifies each device on a network. The MAC address is manufactured into every network card, such as an Ethernet card or Wi-Fi card, and therefore cannot be changed.
  • MHL: Mobile High-Definition Link (MHL) is an industry standard for a mobile audio/video interface that allows consumers to connect mobile phones, tablets, and other portable consumer electronics (CE) devices to high-definition televisions (HDTVs) and audio receivers. The MHL 3.0 standard supports up to 4K (Ultra HD) high-definition (HD) video and 7.1 surround-sound audio, including TrueHD and DTS-HD, while simultaneously charging the connected device. MHL-enabled products include adapters, automotive accessories, AV receivers, Blu-ray Disc players, cables, DTVs, media sticks, monitors, projectors, smartphones, tablets, TV accessories, and more.
  • MIDI: Stands for "Musical Instrument Digital Interface." It is a connectivity standard that musicians use to hook together musical instruments (such as keyboards and synthesizers) and computer equipment. Using MIDI, a musician can easily create and edit digital music tracks. The MIDI system records the notes played, the length of the notes, the dynamics (volume alterations), the tempo, the instrument being played, and hundreds of other parameters, called control changes.

    Because MIDI records each note digitally, editing a track of MIDI music is much easier and more accurate than editing a track of audio. The musician can change the notes, dynamics, tempo, and even the instrument being played with the click of button. Also, MIDI files are basically text documents, so they take up very little disk space. The only catch is that you need MIDI-compatible hardware or software to record and playback MIDI files.
     
  • Mac OS: This is the operating system that runs on Macintosh computers.  The Mac OS has been around since the first Macintosh was introduced in 1984. Since then, it has been continually updated and many new features have been added to it. Each major OS release is signified by a new number (i.e. Mac OS 8, Mac OS 9).
  • Macintosh: This is the name of the computers that are made by Apple Computer. The first Macintosh was introduced in 1984 and was seen as a major innovation in computing ease-of-use. The Macintosh was the first personal computer to use a graphical user interface (GUI), which allowed the user to interact with the operating system by using a mouse to click and drag objects. Since 1984, Apple has continually revised and upgraded the Macintosh product line and now makes both laptop and desktop versions of the Macintosh. The Macintosh product line includes the following models:

    1.       Power Mac - a high-performance desktop computer for professionals
    2.       PowerBook - a high-performance laptop computer for professionals.
    3.       iMac - a creatively designed consumer desktop computer
    4.       iBook - a laptop computer for students and home users
    5.       eMac - an all-in-one desktop computer for educators and entry-level consumers
    6.       Mac mini - a super-small, fully functional computer sold without a monitor, keyboard, or mouse
     
  • Malware: Short for "malicious software," malware refers to software programs designed to damage or do other unwanted actions on a computer system. 

    Common examples of malware include viruses, worms, trojan horses, and spyware. Viruses, for example, can cause havoc on a computer's hard drive by deleting files or directory information. Spyware can gather data from a user's system without the user knowing it. This can include anything from the Web pages a user visits to personal information, such as credit card numbers.
     
     
  • Maximize: Maximizing a window makes it larger. In Windows, a maximized window fills the entire screen, while on a Mac, it takes up only as much space as needed. The maximize button in Windows is located in the upper-right corner of the window, next to the close button. If you double-click the title bar, it will also maximize the window. On a Mac, the maximize button is three green button located next to the red and yellow buttons in the upper-left corner of the window.
  • Mbps: Stands for "Megabits Per Second." One megabit is equal to one million bits or 1,000 kilobits. While "megabit" sounds similar to "megabyte," a megabit is roughly one eighth the size of a megabyte (since there are eight bits in a byte). Mbps is used to measure data transfer speeds of high bandwidth connections, such as Ethernet and cable modems.
  • Megapixel: A megapixel is one million pixels. It is commonly used to describe the resolution of digital cameras. For example, a 7.2 megapixel camera is capable of capturing roughly 7,200,000 pixels. The higher the megapixel number, the more detail the camera can capture. Therefore, the megapixel count is a significant specification to look for when buying a digital camera.
     
    A camera's megapixel number is calculated by multiplying the number of vertical pixels by the number of horizontal pixels captured by the camera's sensor, or CCD. For example, the original Canon Digital Rebel captures 2048 vertical by 3072 horizontal pixels, for a total of 6,291,456 pixels (2048 x 3072). Therefore, it is estimated to be a 6.3 megapixel camera. The Sony T10 captures 3072 x 2304 pixels, totaling 7,077,888, which makes it a 7.2 megapixel camera (because not all the pixels are used).
     
  • Memory: While memory can refer to any medium of data storage, it usually refers to RAM, or random access memory. When your computer boots up, it loads the operating system into its memory, or RAM. This allows your computer to access system functions, such as handling mouse clicks and keystrokes, since the event handlers are all loaded into RAM. Whenever you open a program, the interface and functions used by that program are also loaded into RAM.
  • Menu Bar: A menu bar is a horizontal strip that contains lists of available menus for a certain program. In Windows programs, the menu bar resides at the top of each open window, while on the Mac, the menu bar is always fixed on the top of the screen. Despite this major difference, the menu bar serves the same purpose on each platform.

    Nearly all programs have a menu bar as part of their user interface. It includes menu items and options specific to the particular program. Most menu bars have the the standard File, Edit, and View menus listed first. The File menu includes options such as Save and Open File..., the Edit menu has items such as Undo, Copy, Paste, and Select All, while in the View menu you'll find viewing options such as changing the layout of open windows. Word processing programs, such as Microsoft Word, also include menu options such as Insert, Format, and Font which you will most likely not find in a Web browser's menu bar. But a Web browser may contain menu options such as History and Bookmarks, which you will not find in a word processing program.
     
  • Minimize: Minimizing a window temporarily hides it from view without closing it. In Windows, a button for the minimized window is added to the taskbar. In Mac OS X, a small icon for the window is added to the dock. Clicking the window's button or icon will reopen the window. You can then click the maximize button to increase the window's size.

    To minimize a window in Windows, click the button with a horizontal line icon in the upper-right corner of a window. In Mac OS X, click the yellow button in the upper-left corner of the window or double-click the title bar.
     
  • Modem: The word modem is actually short for Modulator/Demodulator. A modem is a communications device that can be either internal or external to your computer. It allows one computer to connect another computer and transfer data over telephone lines. The original dial-up modems are becoming obsolete because of their slow speeds and are being replaced by the much faster cable and DSL modems.
  • Monitor: The term "monitor" is often used synonymously with "computer screen" or "display." The monitor displays the computer's user interface and open programs, allowing the user to interact with the computer, typically using the keyboard and mouse.
  • Motherboard: The motherboard is the main circuit board of your computer and is also known as the mainboard or logic board. If you ever open your computer, the biggest piece of silicon you see is the motherboard. Attached to the motherboard, you'll find the CPU, ROM, memory RAM expansion slots, PCI slots, and USB ports. It also includes controllers for devices like the hard drive, DVD drive, keyboard, and mouse. Basically, the motherboard is what makes everything in your computer work together.
  • Mouse: A mouse, along with the keyboard, is one of the two main input devices used by computers. It is a small handheld device that tracks the user's motion and is used for moving the cursor on the screen. It also has buttons that are used for clicking and right-clicking objects.
  • mAh: An ampere-hour or amp-hour (Ah) is a unit of electric charge. mAh (milliampere-hour) is one-thousnadth of that. It is a technical term for how much electrical charge a particular battery will hold.
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  • NAS: NAS is short for "Network Attached Storage." It refers to a network storage system in which shared data is stored in a central location, using an NAS server. The NAS server contains one or more hard drives that can be accessed by multiple computers on the network. Most NAS systems allow the network administrator to configure the file sharing settings, including which computers can access the data. NAS systems are used in both business and home networks.
  • NFC: NFC (Near Field Communication) is a short range high frequency wireless communication technology that enables the exchange of data between devices over about a 10cm distance.
  • NIC: Stands for "Network Interface Card." Pronounced "nick," this is the card that physically makes the connection between the computer and the network cable. These cards typically use an Ethernet connection and are available in 10, 100, and 1000 Base-T configurations.
  • NTFS: Stands for "New Technology File System." NTFS is a file system introduced by Microsoft with Windows NT and is supported by subsequent versions of Windows, such as Windows 2000 and Windows XP. NTFS has a number of advantages over the previous file system, named FAT32 (File Allocation Table). One major advantage of NTFS is that it includes features to improve reliability. 
  • NTSC: NTSC is the U.S. standard that was adopted in 1941 as the first standardized television broadcasting and video format in the U.S.. NTSC stands for National Television Standards Committee and was approved by the FCC (Federal Communications Commission) as the standard for television broadcasting in the U.S. Since NTSC was originally developed without consideration for the eventual addition of Color (1953) - the implementation of color into the NTSC format has been a weakness of the system, thus the term for NTSC became known by many professionals as "Never Twice The Same Color".
     
    NTSC is based on a 525-line, 60 fields/30 frames-per-second at 60Hz system for transmission and display of video images. This is an interlaced system in which each frame is scanned in two fields of 262 lines, which is then combined to display a frame of video with 525 scan lines.
     
  • Native Resolution: The computer resolution that optimizes the projector resolution. When buying a projector, you should always match the resolution of your notebook to the native resolution of your projector.
  • Network-Enabled: In the home theater environment, the term "Network-Enabled" refers to a Blu-ray Disc player, TV, or home theater receiver has is equipped with the ability to connect, wired (Ethernet) or wirelessly (Wi-Fi), to a router for accessing PC or media server-based content as part of a home network, or accessing content directly from the internet.
  • Network: When you have two or more computers connected to each other, you have a network. The purpose of a network is to enable the sharing of files and information between multiple systems. The Internet could be described as a global network of networks. Computer networks can be connected through cables, such as Ethernet cables or phone lines, or wirelessly, using wireless networking cards that send and receive data through the air.
  • Noise: Technically, random and non-repeatable signal in an image. In common use in digital photography, any unwanted or undesirable signal that does not convey useful information. For example, a dark frame is composed of thermal current signal, thermal signal noise (and bias). Thermal and bias signals are technically not noise because they are consistently repeatable, and this is how we are able to remove them by subtraction with a calibration frame. Thermal signal noise is random and cannot be removed. However many people refer to thermal current as "noise".
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  • OEM: Stands for "Original Equipment Manufacturer." This refers to a company that produces hardware to be marketed under another company's brand name.
     
  • OS X: Mac OS X, is the current version of the operating system used on Apple Macintosh computers.
  • OSD: OSD is short for "On Screen Display." An OSD is an onscreen menu included with most monitors that allows users to make adjustments to the display. Common OSD settings include brightness, contrast, and color calibration adjustments. Some monitors also include positioning settings and tilt control. You can activate the OSD by pressing the MENU button on the side of the monitor. Once the OSD appears, you can navigate through the menu options and make adjustments using the plus (+) and minus (-) buttons.
  • Offline: When a computer or other device is not turned on or connected to other devices, it is said to be "offline." This is the opposite of being "online," when a device can readily communicate with other devices.

    Offline can also mean not being connected to the Internet. When you disconnect from your ISP or pull out the Ethernet cable from your computer, your computer is offline. Some programs, such as Web browsers and e-mail programs, have an option to "Work Offline." This option disables the program's network connection, meaning no data can be transmitted to or from the computer.
     
  • Online: In general, when a machine is "online," it is turned on and connected to other devices. For example, when a network printer is online, computers connected to that network can print from it. Other devices, such as scanners, video cameras, audio interfaces, and others are said to be online when they are running and connected to a computer system.

    Recently, however, the term "online" usually means being connected to the Internet. The connection can be through a phone line, using a dial-up or DSL modem, a cable line via a cable modem, or through a wireless connection. A computer can also be online via a connection to a computer network. Technically, computers that are on a network are online even if they are not connected to the Internet.
     
  • Operating System: Also known as an "OS," this is the software that communicates with computer hardware on the most basic level. Without an operating system, no software programs can run. The OS is what allocates memory, processes tasks, accesses disks and peripherals, and serves as the user interface.
  • Optical Drive: In the computer world, "optical" refers to lasers, which can "see" and read data on optical discs. These discs include CDs and DVDs, which are made up of millions of small bumps and dips. Optical drives have lasers that read these bumps and dips as ones and zeroes, which the computer can understand.

    Some common types of optical drives include CD-ROM, CD-RW, DVD-ROM, DVD-RW, and Blu-ray drives.
     
  • Outbox: An Outbox is where outgoing e-mail messages are temporarily stored. While you are composing a message, most mail programs automatically save a draft of your message in the Outbox. The message is then stored in the Outbox until it is successfully sent to the recipient. Once the message has been sent, most e-mail programs move the message to the "Sent" or "Sent Messages" folder. While the terms "Outbox" and "Sent Messages" are often used synonymously, technically they have different meanings.
  • Output Device: Any device that outputs information from a computer is called, not surprisingly, an output device. Since most information from a computer is output in either a visual or auditory format, the most common output devices are the monitor and speakers. These two devices provide instant feedback to the user's input, such as displaying characters as they are typed or playing a song selected from a playlist.
  • Overclocking: Overclocking involves increasing the clock speed of the computer's CPU past the rate at which it was originally designed to run.
  • Overwrite: The term "overwrite" refers to replacing old files with new ones. If you try to save a document with the same filename as an existing document, you may be asked if you want to overwrite the file. If you click OK, the old document will be overwritten by the new one. Similarly, when moving files to a folder, the operating system may ask you if you would like to overwrite existing files with the same filenames. If you choose select Overwrite, the old files will be replaced by the new ones.
     
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  • P2P: Stands for "Peer to Peer." In a P2P network, the "peers" are computer systems which are connected to each other via the Internet. Files can be shared directly between systems on the network without the need of a central server. In other words, each computer on a P2P network becomes a file server as well as a client.
  • PAL: PAL (Phase Alternate Line) is the dominant format in the World for analog television broadcasting and video display and is based on a 625 line, 50 field/25 frames a second, 50HZ system. The signal is interlaced, like NTSC into two fields, composed of 312 lines each.
  • PC: Stands for "Personal computer." PCs are are what most of us use on a daily basis for work or personal use. A typical PC includes a system unit, monitor, keyboard, and mouse. Most PCs today also have a network or Internet connection, as well as ports for connecting peripheral devices, such as digital cameras, printers, scanners, speakers, external hard drives, and other components.
  • PCI Express: PCI Express can be abbreviated as PCIe or, less commonly and more confusingly, PCX. Unlike earlier PCI standards, PCI Express does not use a parallel bus structure, but instead is a network of serial connections controlled by a hub on the computer's motherboard. This enables PCI Express cards to run significantly faster than previous PCI cards.
  • PCI: Stands for "Peripheral Component Interconnect." It is a hardware bus designed by Intel and used in both PCs and Macs. Most add-on cards such as SCSI, Firewire, and USB controllers, use a PCI connection. Some graphics cards use PCI, but most new graphics cards connect to the AGP slot. PCI slots are found in the back of your computer and are about 3.5" long and about 0.5" high. So before you go buy that Firewire expansion card, make sure you have at least one PCI slot available.
  • PCMCIA: Stands for "Personal Computer Memory Card International Association. The term is most commonly associated with the actual cards standardized by the organization. These cards are referred to as "PCMCIA cards," or simply "PC cards." There are three types of PCMCIA cards, all of which are rectangular and measure 8.56 by 5.4 cm., but have different widths:

    ·         Type I: up to 3.3 mm. thick, mainly used to add additional ROM or RAM.
    ·         Type II: up to 5.5 mm. thick, typically used for fax/modem cards.
    ·         Type III: up to 10.5 mm. thick, often used to attach portable disk drives.

    PCMCIA slots also come in three sizes -- a Type I slot can hold one Type I card, a Type II slot can hold one Type II card or two Type I cards, and a Type III slot can hold one Type III card or one Type I and one Type II card. PC Cards can be removed or inserted "on the fly," which means you don't have to turn your computer off to exchange them and you don't have to restart for your computer to recognize them.
     
  • PDF: Stands for "Portable Document Format." PDF is a multi-platform file format developed by Adobe Systems. A PDF file captures document text, fonts, images, and even formatting of documents from a variety of applications. You can e-mail a PDF document to your friend and it will look the same way on his screen as it looks on yours, even if he has a Mac and you have a PC. Since PDFs contain color-accurate information, they should also print the same way they look on your screen.
  • PLA Filament: Polyactic Acid (PLA), is another 3D filament which prints at 180 - 200 degrees C without a heated bed. Usually smells sweeter than ABS when printing.
  • PPPoE: PPPoE is short for "Point-to-Point Protocol over Ethernet. It is a protocol commonly used by DSL providers for establishing a PPP connection over an Ethernet network. PPPoE is often seen as an alternative to DHCP, which is the standard network configuration used by cable Internet providers.
  • PRAM: Stands for "Parameter Random Access Memory”, PRAM is a type of memory found in Macintosh computers that stores system settings. These settings include display settings (like screen resolution and color depth), the time zone setting, speaker volume, and the startup volume choice. The system settings that are stored in the computer's PRAM differ from Mac to Mac, but the purpose of the memory remains the same.
  • Parallel Port: This interface is found on the back of older PCs and is used for connecting external devices such as printers or a scanners. It uses a 25-pin connector (DB-25) and is rather large compared to most new interfaces. The parallel port is sometimes called a Centronics interface, since Centronics was the company that designed the original parallel port standard. It is sometimes also referred to as a printer port because the printer is the device most commonly attached to the parallel port. 
  • Partition: A partition is a section of a hard disk. When you format a hard disk, you can usually choose the number of partitions you want. The computer will recognize each partition as a separate disk, and each will show up under "My Computer" (Windows) or on the desktop (Macintosh).
  • Password: A password is a string of characters used for authenticating a user on a computer system. For example, you may have an account on your computer that requires you to log in. In order to successfully access your account, you must provide a valid username and password. This combination is often referred to as a login. While usernames are generally public information, passwords are private to each user.
  • Paste: The paste function can be used to paste copied data into text documents, images, Web browser address fields, and just about any place where you can enter data. However, to paste data, you first need to copy it to the "Clipboard," which is a temporary storage area in your system's memory, or RAM. This is done by first selecting the data you want to copy and then choosing "Copy" from the program's Edit menu.
  • Peripheral: A computer peripheral is any external device that provides input and output for the computer. For example, a keyboard and mouse are input peripherals, while a monitor and printer are output peripherals. Computer peripherals, or peripheral devices, are sometimes called "I/O devices" because they provide input and output for the computer. Some peripherals, such as external hard drives, provide both input and output for the computer.
  • Ping: A ping is a test to see if a system on the Internet is working. "Pinging" a server tests and records the response time of the server. Pinging multiple computers can be helpful in finding Internet bottlenecks, so that data transfer paths can be rerouted a more efficient way.
  • Pixel Density: Pixel Density is the actual amount of physical picture elements on a screen surface or an LCD/DLP projection chip. LCD/DLP projectors have a fixed number of pixels on their chips and LCD/Plasma TVs have a fixed number of pixels on their screen surface.
  • Pixel: The term "pixel" is actually short for "Picture Element." These small little dots are what make up the images on computer displays, whether they are flat-screen (LCD) or tube (CRT) monitors. The screen is divided up into a matrix of thousands or even millions of pixels. Typically, you cannot see the individual pixels, because they are so small. If you set your monitor to a low resolution, such as 640x480 and look closely at your screen, you will may be able to see the individual pixels. As you may have guessed, a resolution of 640x480 is comprised of a matrix of 640 by 480 pixels, or 307,200 in all.
  • Plasma TV: A Plasma television is a type of Flat Panel video display device.

    Plasma television technology is based loosely on the fluorescent light bulb. The display itself consists of cells. Within each cell two glass panels are separated by a narrow gap in which neon-xenon gas is injected and sealed in plasma form during the manufacturing process. The gas is electrically charged at specific intervals when the Plasma set is in use. The charged gas then strikes red, green, and blue phosphors, thus creating a television image. Each group of red, green, and blue phosphors is called a pixel (picture element).
     
  • Plenum Cable: The term “Plenum Cabling” refers to structured cabling laid in the plenum of buildings (the space where air circulation – heating and air conditioning systems – are facilitated.) It has a slow-burning, fire-resistant casing.
  • Plug and Play: Plug and Play, sometimes, abbreviated PnP, is a catchy phrase used to describe devices that work with a computer system as soon as they are connected. The user does not have to manually install drivers for the device or even tell the computer that a new device has been added. Instead the computer automatically recognizes the device, loads new drivers for the hardware if needed, and begins to work with the newly connected device.
  • PoE: Power over Ethernet. The delivery of power to a remote device using the same cable lines used to deliver Ethernet data. This enables a single cable to provide both data and power to devices.
  • Port: This is a number that indicates what kind of protocol a server on the Internet is using. For example, Web servers typically are listed on port 80. Web browsers use this port by default when accessing Web pages, but you can also specify what port you would like to use in the URL like this: http://www.excite.com:80. FTP uses port 21, e-mail uses port 25, and game servers, like a Quake server or Blizzard.net use various other ports.
  • Power Amplifier: In home theater and stereo system applications, a power amplifier is a type of amplifier that supplies power to a speaker or speakers, but does not have any other functions, except for a master gain control (gain is analogous to volume). In other to provide further control, such as surround sound processing, bass and treble control, and input selection, for a power amplifier, a preamplifier must be used.
  • Power Cycle: To power cycle a device means to turn it off and turn it back on again. For example, the user manual of a router may ask you to power cycle the router if it stops responding. This may mean switching the power to OFF and then ON again or may require physically unplugging the device and then plugging it back in again. Power cycling is often synonymous with resetting a device.
     
  • Power Supply: A power supply is a component that regulates and provides power to an electrical device. It receives power from a wall outlet, battery pack, or other electrical source and converts the current and voltage to the correct amount required by the connected device. Most computers have internal power supplies, while other devices may use external power supplies that are attached directly to the power cable.
  • Preamplifier: A Preamplifier is a device in which the user can connect all audio or audio/video source components (such as CD, DVD, or Blu-ray Disc players). The preamplifier then can switch between sources, process audio and/or video, but also supplies an audio output signal to what is referred to as a Power Amplifier. The Power Amplifier then supplies the signal and power needed to the loudspeakers. In other words, you cannot connect speakers directly to a preamplifier, unless they are self-powered speakers.
     
    In home theater, preamplifiers may also be referred to as Control Amplifiers, AV Processors, AV Preamps, or Preamp/Processors due their increasing role in providing both audio decoding/processing and video processing/upscaling capabilities.
     
  • Printer: A printer is an output device that prints documents from a computer. Common printers include inkjet and laser printers. Most inkjet printers can produce color prints, while laser printers are available in both monochrome and color versions. To print a document, select "Print" from the File menu within an application
  • Processor: This little chip is the heart of a computer. Also referred to as the "microprocessor," the processor does all the computations such as adding, subtracting, multiplying, and dividing. For computers, the most popular microprocessor used is the Intel Pentium chip and the AMD chip.
  • Program: Program is a common computer term that can be used as both a noun and a verb. A program (noun) is executable software that runs on a computer. It is similar to a script, but is often much larger in size and does not require a scripting engine to run. Instead, a program consists of compiled code that can run directly from the computer's operating system.
  • Progressive Scan: Progressive scan is a system in which images are displayed on a screen by scanning each line (or row of pixels) in a sequential order rather than an alternate order, as is done with interlaced scan.

    In other words, in progressive scan, the image lines (or pixel rows) are scanned in numerical order (1,2,3) down the screen from top to bottom, instead of in an alternate order (lines or rows 1,3,5, etc... followed by lines or rows 2,4,6).

    By progressively scanning the image onto a screen every 60th of a second rather than "interlacing" alternate lines every 30th of a second, a smoother, more detailed, image can be produced on the screen that is perfectly suited for viewing fine details, such as text, and is also less susceptible to interlace flicker.
     
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  • RAM: Stands for "Random Access Memory," and is pronounced like the male sheep. RAM is made up of small memory chips that form a memory module. These modules are installed in the RAM slots on the motherboard of your computer.
     
    Every time you open a program, it gets loaded from the hard drive into the RAM. This is because reading data from the RAM is much faster than reading data from the hard drive. Running programs from the RAM of the computer allows them to function without any lag time. The more RAM your computer has, the more data can be loaded from the hard drive into the RAM, which can effectively speed up your computer. In fact, adding RAM can be more beneficial to your computer's performance than upgrading the CPU.
     
  • RGB: Stands for "Red Green Blue." It refers to the three hues of light (red, green, and blue, for those of you that are a little slow), that can mix together to form any color. When the highest intensity of each color is mixed together, white light is created. When each hue is set to zero intensity, the result is black. TVs and computer monitors use RGB to create the colorful images you see on the screen.
  • RJ 11: RJ-11 is the standard connector used for 2-pair (4 wire) telephone wiring. It comes in both UTP or untwisted cable.
  • RJ-45: Registered Jack 45. A connector for Ethernet cables.More commonly found on Cat5 and Cat6 cables.
  • RX: RX stands for Receiver unit. It receives the signal being sent by the transmitter.
  • Raw: Unprocessed data directly from the sensor.
  • Readme: A readme file, often named "READ ME" to get the user's attention, is a text file containing useful information about a software program. It often accompanies the program's installer or is installed with the program. A typical readme file contains instructions on how to install the program, how to use the basic functions of the program, and what the program does. It may also include a list of recent updates made to the program. Sometimes the readme file will include warnings and other important notices regarding the operation of the program.
  • Real Time: The transfer of data that returns results so quickly that the process appears to be instantaneous.
  • Recycle Bin: The Recycle Bin in used by Windows computers to store deleted items. It temporarily stores files and folders before they are permanently deleted. You can open the Recycle Bin by double-clicking the icon on the Windows desktop. The Recycle Bin window allows you to delete items individually or restore them to their original location. If you want to permanently remove all items in the Recycle Bin, select "Empty the Recycle Bin" in the left sidebar of the window.
  • Refresh Rate: Computer monitors often have a "maximum refresh rate" listed in their technical specifications. This number, measured in hertz (Hz), determines how many times the screen is redrawn each second. Typical refresh rates for monitors include 60, 75, and 85 Hz. Some monitors support refresh rates of over 100 Hz.
     
    The higher the refresh rate, the less image flicker you will notice on the screen. Typically a refresh rate of less than 60 Hz will produce noticeable flicker, meaning you can tell the screen is being redrawn instead of seeing a constant image. If the refresh rate is too slow, this flicker can be hard on your eyes and may cause them to tire quickly.
     
  • Refresh: Refresh is a command that reloads the contents of a window or Web page with the most current data. For example, a window may list files stored within a folder, but may not track their location in real-time. If the files have been moved or deleted since the window was first opened, the folder contents displayed will be inaccurate. By refreshing the window, a current list of files is displayed.

    Web browsers include a Refresh command, which reloads the contents of a Web page. This is especially useful for dynamic Web pages, which contain content that changes often. For example, a page may include a stock quote, which is updated every few seconds. By refreshing the page, a user can see the latest quote and track how much the stock continues to drop since he bought it. Web developers may also use the Refresh command to view recently published changes to Web pages.
     
  • Remote Access: Remote access is the ability to access your computer from a remote location. In order for a remote access connection to take place, the local machine must have the remote client software installed and the remote machine must have the remote server software installed. Also, a username and password is almost always required to authenticate the connecting user.
  • Repeater: Repeaters have many applications, but in computing they are most commonly used in wireless networks. For example, a Wi-Fi network in a large home may benefit from using one or more repeaters to relay the signal to different areas of the house. Homes that have brick walls or cement floors may also benefit from having a repeater relay the signal around the obstacle. Businesses often use a series of repeaters to create a single wireless network within a large building.
  • Resolution: In photography, Spatial Resolution is the number of pixels that we have in an image, and the size of the space that these pixels are contained in. Two parameters are necessary to specify resolution: the number of pixels per inch or centimeter and the total number of inches or centimeters. More pixels in a given space mean higher resolution. Tonal resolution specifies the number of steps of tone that the dynamic range is divided into.
  • Restore: The word "restore" means to return something to its former condition. Therefore, when you restore a computer or other electronic device, you return it to a previous state. This may be a previous system backup or the original factory settings.
  • Right Click: Most computer mice have at least two mouse buttons. When you press the left one, it is called a left click. When you press the one on the right, it is called a right click. By default, the left button is the main mouse button, and is used for common tasks such as selecting objects and double-clicking.
  • Router: This is a hardware device that routes data from a local area network (LAN) to another network connection. This device assigns IP addresses to the computers or other devices connected to it. When it is connected to a modem, it allows the other devices connected to it (router) to access to the Internet.
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  • S-Video: S-Video refers to analog video connection in which the B/W and Color portions of the signal are transferred separately. The signal is then recombined by the Television or video recording device at the receiving end. The result is less color bleeding and more defined edges than with a standard analog composite video connection.
  • SATA: Stands for "Serial Advanced Technology Attachment," or "Serial ATA." It is an interface used to connect ATA hard drives to a computer's motherboard. SATA transfer rates start at 150MBps, which is significantly faster than even the fastest 100MBps ATA/100 drives
  • SD: Stands for "Secure Digital." It is a type of memory card used for storing data in devices such as digital cameras, PDAs, mobile phones, portable music players, and digital voice recorders. The card is one of the smaller memory card formats, measuring 24mm wide by 32mm long and is just 2.1mm thick. To give the cards some orientation, the top-right corner of each SD card is slanted.
  • SMTP Stands for "Simple Mail Transfer Protocol." This is the protocol used for sending e-mail over the Internet. Your e-mail client (such as Outlook, Live, or Gmail) uses SMTP to send a message to the mail server, and the mail server uses SMTP to relay that message to the correct receiving mail server. Basically, SMTP is a set of commands that authenticate and direct the transfer of electronic mail. When configuring the settings for your e-mail program, you usually need to set the SMTP server to your local Internet Service Provider's SMTP settings.
  • SRS Tru-Surround XT: Tru-Surround XT is a sound-scheme that has the ability to take multi-channel encoded sources, such as Dolby Digital, and reproduce the multi-channel surround effect by just using two-speakers. The result is not as impressive as true Dolby Digital 5.1 (the front and side surround effects are impressive, but the rear surround effects fall a little short, with the sense they are coming from just to rear of your head rather than from the back of the room).
  • SSD: SSD is short for "Solid State Drive." An SSD serves the same purpose as a (hard drive/hard drive), but uses flash memory rather than spindle of magnetic disks. It is called a "solid state drive" because it has no moving parts. Since SSDs do not need to move a physical drive head to read data, they can access data faster than hard drives.
  • SSID: Stands for "Service Set Identifier." An SSID is a unique ID that consists of 32 characters and is used for naming wireless networks. When multiple wireless networks overlap in a certain location, SSIDs make sure that data gets sent to the correct destination.
     
    The SSID is different than the name that is assigned to a wireless router. For example, the administrator of a wireless network may set the name of the router, or base station, to "Office." This will be the name that users see when browsing available wireless networks, but the SSID is a different 32 character string that ensures the network name is different from other nearby networks.
     
  • STB: Set-Top Box. A device for decoding incoming AV signals, such as programs from a cable or satellite TV network. Almost all STBs currently rely on HDMI output.
  • SVGA: Acronym for Super Video Graphics Display. SVGA is used to define a specific display resolution equating to 800x600 pixels.
  • SXGA: Acronym for Super Extended Graphics Adapter. SXGA is used to define a specific display resolution equating to 1280x1024 pixels.
  • Safe Mode: Safe Mode is a way for the Windows operating system to run with the minimum system files necessary. It uses a generic VGA display driver instead of the vendor-specific driver. Safe Mode also turns off all third-party drivers for other peripherals such as mice, keyboards, printers, and scanners. In basic Safe Mode, networking files and settings are not loaded, meaning you won't be able to connect to the Internet or other computers on a network.
  • Sampling: Measurement in discrete, regular intervals. Spatial sampling in a digital camera is done by the number of pixels in a given sized area sensor. Tonal sampling is determined by the bit-depth of the analog to digital converter. Correct spatial sampling in high-resolution astrophotography matches the sample size (pixel size) to the size of the Airy disk and seeing, based on the Nyquist sampling theorem.
  • Saturation: 1.) Tonal or pixel values on the bright end of the dynamic range that are maxed out and contain no detail.
    2.) The purity or vividness of a color.
  • Scaling: 1.) Changing the black or white endpoints in image histogram to modify the data so that it changes its distribution in the dynamic range.
    2.) Enlarging or reducing the size of an image.
  • Scanner: A scanner is an input device that scans documents and images, which can be imported into a computer. They are available in flatbed or sheet-fed versions and are usually connected via a high-speed USB port. OCR software can be used to recognize text documents imported from a scanner.
  • Screenshot: A screenshot, or screen capture, is a picture taken of your computer's desktop. This may include the desktop background, icons of files and folders, and open windows. It may also include whatever is being displayed by currently running programs. Screenshots are and easy way to save something you see on the screen, such as an open window, image, or text article. However, because screenshots are saved in an image format, the text saved in a screenshot will not be editable.
  • Scroll Bar: When the contents of a window are too large to be displayed entirely within the window, a scroll bar will appear. For example, if a Web page is too long to fit within a window, a scroll bar will show up on the right-hand side of the window, allowing you to scroll up and down the page. If the page is too wide for the window, another scroll bar will appear at the bottom of the window, allowing you to scroll to the left and right. If the window's contents fit within the current window size, the scroll bars will not appear.
  • Scroll Wheel: The scroll wheel typically sits between the left and right buttons on the top of a mouse. It is raised slightly, which allows the user to easily drag the wheel up or down using the index finger. Pulling the scroll wheel towards you scrolls down the window, while pushing it away scrolls up. Most modern mice include a scroll wheel, since it eliminates the need to move the cursor to the scroll bar in order to scroll through the window. Therefore, once you get accustomed to using a scroll wheel, it can be pretty difficult to live without.
  • Scrolling: Most computer programs display their content within a window. However, windows are often not large enough to display their entire content at once. Therefore, you may have to scroll through the window to view the rest of the contents. For example, on some monitors, a page from a word processing document may not fit within the main window when viewed at 100%. Therefore, you may have to scroll down the window to view the rest of the page. Similarly, many Web pages do not fit completely within a window and may require you to scroll both vertically and horizontally to see all the content.
  • Serial Port: The serial port is a type of connection on PCs that is used for peripherals such as mice, gaming controllers, modems, and older printers. It is sometimes called a COM port or an RS-232 port, which is its technical name. 
  • Server: As the name implies, a server serves information to computers that connect to it. When users connect to a server, they can access programs, files, and other information from the server. Common servers are Web servers, mail servers, and LAN servers. A single computer can have several different server programs running on it.
  • Short Circuit The condition caused when a current flow is interrupted short of or before reaching the device terminating the cable. A short circuit is caused when a hot conductor comes into contact with neutral or ground conductors.
  • Single Band IR:  Single band extenders only work in the first band. This works for almost all DVD and blu ray players.
  • Smartphone: A smartphone combines standard mobile phone features with advanced features found on personal device assistants (PDAs). Most smartphones include e-mail and Web surfing capabilities, as well as the ability to display photos, and play music and video files.
     
    Smartphones have advanced system software, much like a computer operating system, which allows them to perform multiple functions. Many smartphones now support third-party applications or "apps," which users can install on the phone.
     
  • Spam: "Spam" refers to junk e-mail or irrelevant postings to a newsgroup or bulletin board. The unsolicited e-mail messages you receive about refinancing your home, reversing aging, and losing those extra pounds are all considered to be spam.
  • Speakers: Speakers are popular output devices used with computer systems. They receive audio input from the computer's sound card and produce audio output in the form of sound waves.
  • Spyware: Spyware can capture information like Web browsing habits, e-mail messages, usernames and passwords, and credit card information. If left unchecked, the software can transmit this data to another person's computer over the Internet.
  • Standby: When electronic devices are receiving power but are not running, they are in standby mode. For example, a television is in standby mode when it is plugged in, but turned off. While the TV is not "on," it is ready to receive a signal from the remote control. An A/V receiver is also in standby mode when it is plugged in and turned off. This is because the receiver may be activated by receiving input from a connected device or by being turned on directly with the remote control. In other words, these devices are "standing by," waiting to receive input from the user or another device.
     
    When a computer is in standby mode, it is not completely turned off. Instead, it has already been turned on, but has gone into "sleep" mode. Therefore, when referring to computers, "Sleep" and "Standby" may be used synonymously. A computer in standby mode requires a small amount of current, called a "trickle charge," that keeps the current state of running software saved in the computer's RAM. However, because the computer is in sleep mode, the CPU, video card, and hard drive are not running. Therefore, the computer uses very little power in standby mode.
     
  • Storage Capacity: Storage capacity is another term for "disk space." It measures how much data a computer system may contain. For example, a computer with two 750GB hard drives has a storage capacity of 1.5TB. Storage capacity is commonly included in the technical specifications of a system, along with processing power and memory. It is possible to increase the storage capacity of most systems by adding additional internal or external hard drives.
  • Streaming: Data streaming, commonly seen in the forms of audio and video streaming, is when a multimedia file can be played back without being completely downloaded first. Certain audio and video files like Real Audio and QuickTime documents can be streaming files, meaning you can watch a video or listen to a sound file while it's being downloaded to your computer. With a fast Internet connection, you can actually stream live audio or video to your computer. Netflix, Hulu, and Youtube are examples of sites that stream video and audio. 
  • Stretching: Redefining the black or white points in an image to increase the contrast.
  • Subnet Mask: A subnet mask is a number that defines a range of IP addresses that can be used in a network. (It is not something you wear on your head to keep subnets out.) Subnet masks are used to designate subnetworks, or subnets, which are typically local networks LANs that are connected to the Internet. Systems within the same subnet can communicate directly with each other, while systems on different subnets must communicate through a router. Therefore, subnetworks can be used to partition multiple networks and limit the traffic between them.
  • Subwoofer: A subwoofer is a speaker that is specifically designed only to reproduce the lowest of audible frequencies. It is dedicated to the reproduction of low-pitched audio frequencies known as bass.
  • Surge Protector: The surge protector is an important part of any setup. It allows multiple devices to plug in to it at one time and protects each connected device from power surges. For example, a home office may have a computer, monitor, printer, cable modem, and powered speakers all plugged into one surge protector, which is plugged into a single outlet in the wall. The surge protector allows many devices to use one outlet, while protecting each of them from electrical surges.
     
    Surge protectors, sometimes called power strips, prevent surges in electrical current by sending the excess current to the grounding wire (which is the round part of the plug below the two flat metal pieces on U.S. outlet plugs). If the surge is extra high, such as from a lightning strike, a fuse in the surge protector will blow and the current will prevented from reaching any of the devices plugged into the surge protector. This means the noble surge protector will have given its life for the rest of the equipment, since the fuse is destroyed in the process.
     
  • Surround Sound: Surround sound is a term applied to several types of processes that enable the listener to experience sound coming from all directions, depending on the source material.
  • System Requirements: Whenever you purchase software or hardware for your computer, you should first make sure your computer supports the system requirements. These are the necessary specifications your computer must have in order to use the software or hardware. For example, a computer game may require your computer to have Windows XP or later, a 2.0 GHz processor, 512 MB or RAM, a 64 MB graphics card, and 500 MB or hard drive space. If your computer does not meet all of these requirements, the game will not run very well or might not run at all.
  • System Resources: Your computer has many types of resources. They include the CPU, video card, hard drive, and memory. In most cases, the term "system resources" is used to refer to how much memory, or RAM, your computer has available.
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  • TCP/IP: Stands for "Transmission Control Protocol/Internet Protocol." These two protocols were developed in the early days of the Internet by the U.S. military. The purpose was to allow computers to communicate over long distance networks. The TCP part has to do with the verifying delivery of the packets. The IP part refers to the moving of data packets between nodes. TCP/IP has since then become the foundation of the Internet. Therefore, TCP/IP software is built into all major operating systems, such as Unix, Windows, and the Mac OS.
  • TMDS: Transition Modulated Differential Signaling. A technology for transmitting serial data at very high speeds. TMDS is a core technology used in both DVI and HDMI.
  • TX: TX stands for Transmitter unit. Transmits the signal to the reciver unit.
  • Task Bar: The task bar was introduced with Windows 95 and has been part of every version of Windows since then. It is the bar that spans the bottom of the screen and contains the Start button on the left side and the systray on the right. The task bar also includes the current time on the far right side and can hold shortcuts to programs directly to the right of the Start button.
  • Template: A template is a file that serves as a starting point for a new document. When you open a template, it is pre-formatted in some way. For example, you might use template in Microsoft Word that is formatted as a business letter. The template would likely have a space for your name and address in the upper left corner, an area for the recipient's address a little below that on the left site, an area for the message body below that, and a spot for your signature at the bottom.
  • Terabyte: A terabyte is 2 to the 40th power, or 1,099,511,627,776 bytes.
    It can be estimated as 10 to the 12th power, or 1,000,000,000,000 bytes. A terabyte is 1,024 gigabytes.
     
  • Third Party: Third party software refers to software programs developed by companies other than the operating system developer. It may also refer to third party plug-ins, which are developed by other companies besides the original application developer.
  • Throughput: Throughput refers to how much data can be transferred from one location to another in a given amount of time. It is used to measure the performance of hard drives and RAM, as well as Internet and network connections.
  • Throw Distance: Also known as projection distance. Throw distance is the distance from the projector to the screen.
  • Thumbnail: A thumbnail is the nail on your thumb. If you look at your thumbnail, you will notice it is rather small in size. This is why the term "thumbnail" is also used to refer to a reduced size version of a digital image. While digital thumbnails might not always be as small as a human thumbnail, they are usually less than 200x200 pixels in size.
  • Title Bar: A title bar is the section at the top of a window that contains the name or description of the window. Nearly all windows displayed on your computer have a title bar. Therefore, if several windows are tiled across the screen at one time, a user can identify each window by just glancing at the title bar. Windows makes this even easier by placing the information from each window's title bar in the Task Bar. Mac OS X displays the title bar information in the middle of each window when the Exposé function is active.
  • Toolbar: A toolbar is a set of icons or buttons that are part of a software program's interface or an open window. When it is part of a program's interface, the toolbar typically sits directly under the menu bar. For example, Adobe Photoshop includes a toolbar that allows you to adjust settings for each selected tool. If the paintbrush is selected, the toolbar will provide options to change the brush size, opacity, and flow. Microsoft Word has a toolbar with icons that allow you to open, save, and print documents, as well as change the font, text size, and style of the text. Like many programs, the Word toolbar can be customized by adding or deleting options. It can even be moved to different parts of the screen.
  • Toslink: Toslink is a type of digital audio connection developed by Toshiba Corporation. It uses a fiber optic cable to transmit an audio signal in the form of pulses of light. A single Toslink cable can be used to carry a mono, stereo, or even a surround audio signal.

    Toslink is similar to the Sony/Philips Digital Interfance, known as S/PDIF. It provides the same digital audio data as S/PDIF, but uses a light beam instead of an electrical current to send the data. Because the Toslink cable does not use electrical currents, the connection is immune to electrical or magnetic interference. Toslink connections are most commonly found on high-end home theater receivers, MiniDisc players, and professional audio equipment.
     
  • Troffer A large recessed luminaire that is typically flush-mounted on a ceiling.

  • Troubleshooting: Troubleshooting is the process or identifying and fixing problems. Computer troubleshooting may involve hardware or software and can sometimes involve both at the same time. The basic process of troubleshooting is to check the most general possible problems first, and then gradually check for more specific problems. This provides a logical approach to problem solving and can apply to multiple types of products.
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  • UPnP: Stands for "Universal Plug and Play." Plug and Play describes devices that work with a computer system as soon as they are connected. UPnP is an extension of this idea that expands the range of Plug and Play devices to networking equipment. Universal Plug and Play uses network protocols to allow a wide range of devices to be interconnected and work seamlessly with each other.

    UPnP devices can be connected via wired (i.e. Ethernet and Firewire) or wireless (i.e. Wi-Fi and Bluetooth) connections. As long as a product supports UPnP, it can communicate with other UPnP devices within a network. The connections are typically created using the DHCP networking protocol, which assigns each connected device a unique IP address.
     
  • URL: Stands for "Uniform Resource Locator." A URL is the address of a specific Web site or file on the Internet. It cannot have spaces or certain other characters and uses forward slashes to denote different directories. Some examples of URLs are http://www.cnet.com/, http://web.mit.edu/, and ftp://info.apple.com/. As you can see, not all URLs begin with "http". The first part of a URL indicates what kind of resource it is addressing. Here is a list of the different resource prefixes:

    ·         http - a hypertext directory or document (such as a Web page)
    ·         ftp - a directory of files or an actual file available to download
    ·         gopher - a gopher document or menu
    ·         telnet - a Unix-based computer system that you can log into
    ·         news - a newsgroup
    ·         WAIS - a database or document on a Wide Area Information Search database
    ·         file - a file located on your hard drive or some other local drive
     
  • USB: Stands for "Universal Serial Bus." USB is the most common type of computer port used in today's computers. It can be used to connect keyboards, mice, game controllers, printers, scanners, digital cameras, and removable media drives, just to name a few. 
  • UXGA: Resolution of a computer generated image. A UXGA projector will be able to display a 1600x1200 image from a computer running in a UXGA video mode. If the computer is not running in a UXGA mode, typically the projector will resize the image to 1600x1200.
  • Unbalanced Audio:  In electronics, a condition where the two legs of the circuit are unbalanced with respect to ground, usually because one leg is kept at ground potential. In other words: An audio signal requires two wires or conductors to function. Unbalanced circuits tend to be less expensive to construct, but they are much more susceptible to induced noise problems than their balanced counterparts.
  • Undo: The Undo command is located in the Edit menu of most programs and has the shortcut "Ctrl+Z" (PC) or "Cmd-Z" (Mac). It is used to undo the most recent action performed in a program. Common events that can be undone include typing or deleting text in a word processing program, drawing or moving images in an image editor, and trimming media in a video or audio editing program. By selecting "Undo," most actions can be quickly reversed. Many programs also support "multiple undo," which makes it possible to undo several actions at once.
  • Unmount: Unmounting a disk makes it inaccessible by the computer. Of course, in order for a disk to be unmounted, it must first be mounted. When a disk is mounted, it is active and the computer can access its contents. Since unmounting a disk prevents the computer from accessing it, there is no risk of the disk being disconnected in the middle of a data transfer. Therefore, before removing an external data storage device, such as a USB flash drive, the disk should be unmounted to avoid possible data corruption.
  • Upload: While downloading is receiving a file from another computer, uploading is the exact opposite. It is sending a file from your computer to another system. Pretty straight forward. It is possible to upload and download at the same time, but it may cause slower transfer speeds, especially if you have a low bandwidth connection. Because most files are located on Internet servers, people generally do a lot more downloading than uploading.
  • User Interface: A user interface is the means in which a user controls a software program or hardware device. For example, a software interface may include windows, icons, menus, and buttons that allow the user to interact with the program. This is also known as a graphical user interface, or GUI. A hardware interface can be a remote control or a video game controller. It may also refer to the controls on a camcorder, digital camera, or iPod. Most modern user interfaces today are designed using a combination of hardware and software.
  • Username: A username is a name that uniquely identifies someone on a computer system. For example, a computer may be setup with multiple accounts, with different usernames for each account. Many websites allow users to choose a username so that they can customize their settings or set up an online account. For example, your bank may allow you to choose a username for accessing your banking information. You may need to choose a username in order to post messages to a certain message board on the Web. E-mail services, such as Live.com mail require users to choose a username in order to use the service.
  • Utility: Utility programs, commonly referred to as just "utilities," are software programs that add functionality to your computer or help your computer perform better. These include antivirus, backup, disk repair, file management, security, and networking programs. Utilities can also be applications such as screensavers, font and icon tools, and desktop enhancements. Some utility programs help keep your computer free from unwanted software such as viruses or spyware, while others add functionality that allows you to customize your desktop and user interface.
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  • VGA: Stands for "Video Graphics Array." It is the standard monitor or display interface used in most PCs. Therefore, if a monitor is VGA-compatible, it should work with most new computers. The VGA standard was originally developed by IBM in 1987 and allowed for a display resolution of 640x480 pixels. Since then, many revisions of the standard have been introduced. The most common is Super VGA (SVGA), which allows for resolutions greater than 640x480, such as 800x600 or 1024x768. A standard VGA connection has 15 pins and is shaped like a trapezoid.
  • VPN: Stands for "Virtual Private Network" (not a successor to the UPN television network). VPN is a network term that most computer users don't need to know, but at least you can impress your friends by talking about it. A virtual private network is "tunneled" through a wide area network WAN such as the Internet. This means the network does not have to be located in one physical location like a LAN. However, by using encryption and other security measures, a VPN can scramble all the data sent through the wide area network, so the network is "virtually" private.
  • VRAM: Stands for "Video Random Access Memory" and is pronounced "V-RAM." System RAM is great for loading and running programs, but when you need graphics power, VRAM is where it's at. This is the memory used to store image data that the computer displays; it acts as a buffer between the CPU and the video card. When a picture is to be displayed on the screen, the image is first read by the processor and then written to the VRAM. The data is then converted by a RAM digital-to-analog converter (RAMDAC) into analog signals that are sent to the display. Of course, the whole process happens so quickly, you don't notice it. Unlike most system RAM, VRAM chips are dual-ported, which means that while the display is reading from VRAM to refresh the currently displayed image, the processor is writing a new image to the VRAM. This prevents the display from flickering between the redrawing of images.
     
  • Varifocal Lens: A lens that has three focal elements contained in a single assembly.
  • Video Card: Most of the processing done on a computer is done via the computer's central processing unit, or CPU. So in order to give the CPU a break and help it run more efficiently, a video card can be used to process the graphics portion of the processing load. Because most of today's programs are graphically oriented, the video card can help almost any program run more efficiently. However, the difference in performance is especially noticeable in image editing applications and 3D games.

    Video cards, also called graphics accelerators, can speed up both 2D and 3D graphics rendering. Programs such as photo editors and Web browsers may benefit from 2D acceleration, while CAD design programs and video games will most likely benefit from the card's 3D acceleration. Some programs rely so heavily on the video card, that they will not run if a supported video card is not installed.
     
  • Virus: Computer viruses are small programs or scripts that can negatively affect the health of your computer. These malicious little programs can create files, move files, erase files, consume your computer's memory, and cause your computer not to function correctly. Some viruses can duplicate themselves, attach themselves to programs, and travel across networks. In fact opening an infected e-mail attachment is the most common way to get a virus.
  • VoIP: Stands for "Voice Over Internet Protocol," and is often pronounced "voip." VoIP is basically a telephone connection over the Internet. The data is sent digitally, using the Internet Protocol (IP) instead of analog telephone lines. This allows people to talk to one another long-distance and around the world without having to pay long distance or international phone charges.

    In order to use VoIP, you need a computer, an Internet connection, and VoIP software. You also need either a microphone, analog telephone adapter, or VoIP telephone. Many VoIP programs allow you to use a basic microphone and speaker setup. Others requires VoIP phones, which are like regular telephone handsets, but typically connect to your computer via USB. Analog telephone adapters allow you to use regular phones with your computer. IP phones are another option that connect directly to a router via Ethernet or wirelessly. These phones have all the necessary software for VoIP built in and therefore do not require a computer.
     
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  • WAN: Stands for "Wide Area Network." It is similar to a Local Area Network (LAN), but it's a lot bigger. Unlike LANs, WANs are not limited to a single location. Many wide area networks span long distances via telephone lines, fiber optic cables, or satellite links. They can also be composed of smaller LANs that are interconnected. The Internet could be described as the biggest WAN in the world.
  • WEP: Stands for "Wired Equivalent Privacy." WEP is a security protocol for Wi-Fi networks. Since wireless networks transmit data over radio waves, it is easy to intercept data or "eavesdrop" on wireless data transmissions. The goal of WEP is to make wireless networks as secure as wired networks, such as those connected by Ethernet cables.
  • WLAN Wireless local area network. Instead of wires, stations on a WLAN connect to each other through radio waves. The IEEE 802.11, family of standards guides the development of WLANs.
  • WPA: Wi-Fi Protected Access. A security protocol developed by the Wi-Fi Alliance to secure wireless networking takes the place of WEP; the most secure version is WPA2.
  • WSXGA: WSXGA defines a class of SXGA displays with a width resolution sufficient to create an aspect ratio of 16:9. Resolution is defines by the number of individual dots (pixels) that a display uses to create an image. A WSXGA display has 1920 to 1600 horizontal pixels and 1080 to 900 vertical pixels respectively that are used to compose the image delivered by the projector.
  • WXGA: WXGA defines a class of XGA displays with a width resolution sufficient to create an aspect ratio of 16:9. Resolution is defines by the number of individual dots (pixels) that a display uses to create an image. A WXGA display has 1366 to 1280 horizontal pixels and 768 to 720 vertical pixels respectively that are used to compose the image delivered by the projector.
  • Watt A watt is an electrical unit measure that indicates the amount of electrical power on a circuit.
  • Web Browser: A Web browser, often just called a "browser," is the program people use to access the World Wide Web. It interprets HTML code including text, images, hypertext links, Javascript, and Java applets. After rendering the HTML code, the browser displays a nicely formatted page. Some common browsers are Microsoft Internet Explorer, Google Chrome, and Safari.
  • Web Page: Web pages are what make up the World Wide Web. These documents are written in HTML (hypertext markup language) and are translated by your Web browser. Web pages can either be static or dynamic. Static pages show the same content each time they are viewed. Dynamic pages have content that can change each time they are accessed. These pages are typically written in scripting languages such as PHP, Perl, ASP, or JSP. The scripts in the pages run functions on the server that return things like the date and time, and database information. All the information is returned as HTML code, so when the page gets to your browser, all the browser has to do is translate the HTML.

    Please note that a Web page is not the same thing as a Web site. A Web site is a collection of pages. A Web page is an individual HTML document. This is a good distinction to know, as most techies have little tolerance for people who mix up the two terms.
     
  • Webcam: Webcams are typically small cameras that either attach to a user's monitor or sit on a desk. Most webcams connect to the computer via USB, though some use a Firewire connection. Webcams typically come with software that allows the user to record video or stream the video on the Web. If the user has a website that supports streaming video, other users can watch the video stream from their Web browsers.
     
    Webcams can also be used for video chat sessions with other people. Instead of broadcasting the video on the Web, users can set up a video chat session with one or more friends and have a conversation with live audio and video. For example, Apple's iSight camera, which is built into Apple laptops and iMacs, allows users to video chat using the iChat instant messaging program. Several other chat programs also work with webcams, allowing users to set up video chat sessions with friends.
     
  • Website: A website, or Web site, is not the same thing as a Web page. Though the two terms are often used interchangeably, they should not be. So what's the difference? To put it simply, a Web site is a collection of Web pages.
  • Wi-Fi: Wi-Fi is a wireless networking standard trademarked by the Wi-Fi Alliance. It refers to all networking equipment that is based on one of the IEEE 802.11 standards. Wi-Fi allows computers and other devices to connect to wireless routers and therefore other systems on the network. If the router is connected to the Internet, devices connected to the wireless access point may also have Internet access.
  • Widget: Widgets are small programs designed for the Mac OS X Dashboard. Some widgets included with Mac OS X include a dictionary, calendar, weather forecast, and stock list widget. Several thousand other dashboard widgets are available from third-party developers.
  • Window: A window is an area on the screen that displays information for a specific program. This often includes the user interface GUI as well as the program content. Windows are used by most applications as well as the operating system itself. A typical window includes a title bar along the top that describes the contents of the window, followed by a toolbar that contains user interface buttons. Most of the window's remaining area is used to display the content.
  • Windows: Microsoft Windows is the most popular operating system for personal computers. There are several versions of the Windows operating system, including Windows XP (for home users) and Windows 2000 (for professional users). Earlier versions of Windows include Windows 3.1, 95, 98, ME, and NT. All Windows platforms use a graphical user interface (GUI), like the Mac OS, and also offer a command-line interface for typing text commands.
  • Wireless: In the computing world, the term "wireless" can be rather ambiguous, since it may refer to several different wireless technologies. The two most common types of wireless capabilities computers have are Wi-Fi and Bluetooth.
  • Woofer A loudspeaker that reproduces bass frequency.
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  • XGA: Acronym for Extended Graphics Adapter. A graphics standard introduced by IBM that includes VGA and extended resolution up to 1024x768 pixels.
  • XLR connector A type of audio connector featuring three leads: two for the signal and one for overall system grounding. A secure connector often found on high quality audio and video equipment, also called a cannon connector. Trademarked name for circular 3-pin connectors developed by Cannon (now owned by ITT). "XLR" was originally nothing more than Cannon's part designation for the connector. In fact, you'll also sometimes see these connectors referred to as "Cannon" connectors. XLR has since evolved into a generic industry term, and many manufacturers now make this style connector. In audio work, XLR connectors are normally used for transmitting balanced mic and line level signals. Pin 1 of an XLR connector is always ground/shield. The connectors are designed so that pin 1 makes its connection first when inserted in a jack; this ensures that the ground connection is made first, helping prevent pops and thumps in the audio chain. Either pin 2 or pin 3 may be hot (determined by the gear the connector is plugged into), with the remaining pin being cold. To maintain correct polarity in a signal path, it is important to be aware of which pin is hot or cold on all connections, and wire your cables accordingly.

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  • Y, Cb, Cr: Y,Cb,Cr when it first appeared on DVD players and TVs often times referred to an interlaced scan-only compatible component video connection. However, that use of the label is actually incorrect. The designation Y,Cb,Cr, if used correctly, refers to an digitally transferred component video signal, which is used in the PC and professional video environments.
  • Y, Pb, Pr: Y,Pb,Pr refers to an analog component video signal that is passed by a component video connection that uses three RCA-type connectors and cables (red, green, blue) from a source device, such as DVD or Blu-ray Disc player, to a home theater receiver, TV, or video projector.
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  • Zip: Windows users will see this term a lot when looking for files on the Internet. A zip file (.zip) is a "zipped" or compressed file. For example, when you download a file, if the filename looks like this: "filename.zip," you are downloading a zipped file. "Zipping" a file involves compressing one or more items into a smaller archive. A zipped file takes up less hard drive space and takes less time to transfer to another computer.
  • Zone A single room, a group of rooms, or an entire house in which automated or centrally located devices are controlled from a single controller. For example, in an audio zone all occupants hear the same audio playback.
  • Zone 2: On a home theater receiver, the Zone 2 feature allows a second source signal to speakers or a separate audio system in another location. This is not the same as just connecting additional speakers and placing them in another room.

    The Zone 2 feature allows control of either the same, or separate, source than the one being listened to in the main room, in another location. For example, the user can be watching a Blu-ray Disc or DVD movie with surround sound in the main room, while someone else can listen to a CD player in another room, at the same time. Both the Blu-ray Disc or DVD player and CD player are connected to the same Receiver, but are accessed and controlled separately using the same main Receiver.
     
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