San Diego State University

Glossary of Academic Information Technology Terms


Please be aware that our collection of glossary terms is a compilation from many un-attributed sources. If you are aware of a term missing from this listing and would like it added, please send the term and its definition information via Email to for inclusion consideration.

N or Return to Quick Index

Software that's written specifically to run on a particular processor. For example, a program optimized for a 68K processor runs in native mode on a Quadra, but it runs in emulation mode (which is slower on a Power PC-based Power Mac). Also, the file format in which an application normally saves it documents. The native format is generally readable only by that application (other programs can sometimes translate it using filters).

Navigation Tools
Allows users to find their way around a website or multimedia presentation. They can be hypertext links, clickable buttons, icons, or image maps.

A form of online etiquette. This term refers to an informal code of conduct that governs what is generally considered to be the acceptable way for users to interact with one another online.

A term often used to denote USENET news, a popular forum for discussion on the Internet.

A discussion group, usually found on USENET news. Each group devotes its discussions to a specific topic.

A software program that lets you subscribe to newsgroups as well as read and post messages to them.

news server
A machine that contains a number of USENET newsgroups. Also referred to a NNTP server.

The chief priest of network operating systems.

In general, a group of computers set up to communicate with one another. Your network can be a small system that's physically connected by cables (a LAN), or you can connect separate networks together to form larger networks (called WANs). The Internet, for example, is made up of thousands of individual networks.

Network File System. A protocol developed by Sun Microsystems which allows a computer system to access files over a network as if they were on its local disks. This protocol has been incorporated in products by more than two hundred companies, and is now a de facto Internet standard.

Network Information Center. A organization that provides information, assistance and services to network users.

Network Operations Center. A location from which the operation of a network or internet is monitored. Additionally, this center usually serves as a clearinghouse for connectivity problems and efforts to resolve those problems.

A computer that is attached to a network; sometimes called a host.

In the scanning context, this refers to random, incorrectly read pixel values, normally due to electrical interference or device instability.

Image compression without loss of quality.

National Science Foundation Network. The NSFNET is a high speed network of networks which is hierarchical in nature. At the highest level is a backbone network which spans the continental United States. Attached to that are mid-level networks and attached to the mid-levels are campus and local networks. NSFNET also has connections out of the U.S. to Canada, Mexico, Europe, and the Pacific Rim. The NSFNET is part of the Internet.


O or Return to Quick Index

Generally used to describe an illustration or font file as being created by mathematical equations. Also see Bit-map.

Optical Character Recognition. A technology that lets you scan a printed page (with a scanner) and convert it into text document that you can edit in a word processor.

Offset lithography
A high-volume, ink-based printing process, in which ink adhering to image areas of a lithographic plate is transferred (offset) to a blanket cylinder before being applied to paper or other substrate.

Actively connected to other computers or devices. You're on-line when you've logged on to a network, BBS, or on-line service. A device such as a printer is on-line when it's turned on and accessible to a computer. If you're not on-line then you're off-line.

On-line Service
A commercial service that (for a price) provides goodies such as e-mail, discussion forums, tech support, software libraries, news, weather reports, stock prices, plane reservations, even electronic shopping malls. To access one, you need a modem. Popular on-line services include America Online, CompuServe, and Prodigy.

Operating System
Software that supervises and controls tasks on a computer.

Optical Resolution
In the scanning context, this refers to the number of truly separate readings taken from an original within a given distance, as opposed to the subsequent increase in resolution (but not detail) created by software interpolation.

Optical Video Disc
Compact discs which use lights to read information.

Open Systems Interconnection, a set of standard protocol grouped into seven layers: the physical, data link, network, transport, session, presentation, and application layers.


P or Return to Quick Index

Public Access Catalog. The SDSU University Library's on-line catalog which lists the books held here and the journals subscribed to (but not their contents. It also provides information on circulation status, books and journals ordered but not yet received, receipt of journal issues, and more.

The unit of data sent across a packet switching network. While some Internet literature use the term to refer specifically to data sent across a physical network, other literature views the Internet as a packet switching network and describes IP Datagrams as packets.

Data transmission process, utilizing addressed packets, whereby a channel is occupied only for the duration of the packet transmission. SDSUnet is a are packet-switching network.

The oldest and most limited Macintosh graphic file format, holding only black-and-white bit maps at 72 dpi. Paint files (file type PNTG) are limited to 8 by 10 inches.

Parallel Cable/Parallel Port
A cable used to connect peripheral devices through a computer's parallel port. A type of port that transmits data in parallel (several bits side by side).

A word, number, or symbol that is typed after a command to further specify how the command should function.

A check bit used to make the sum of the bits in a unit of data either even or odd (including the parity bit). A unit of data that is 8 bits long would have no parity, and a unit of data 7 bits long would have an even parity bit to make an 8 bit word. Parity is used to check a unit of data for errors during transmission through phone lines or null modem cables.

To insert information from the Clipboard. Information can be pasted multiple times.

A route used in finding, retrieving, and storing files on a disk. The course leading from the root directory of a drive to a particular file.

The Practical Extraction and Report Language. An interpreted language for CGI scripts.

A standard format for credit-card-size expansion cards, used to add features to laptop computers, hand-held computers, and desktop computers. The acronym stands for Personal Computer Memory Card International Association.

Portable Document Format. A PDF file is an electronic facsimile of a printed document.

A network setup that allows every computer to both offer and access network resources, such as shared files, without requiring a centralized file server. Macintosh computers utilize this type of network setup.

A piece of hardware that's outside the main computer. It usually refers to external hardware such as disk drives, printers, and scanners sold by a third party.

Practical Extraction and Reporting Language. A robust programming language frequently used for creating CGI programs on web servers.

The standard macintosh graphic file format for animations. Essentially a collection of bit-mapped PICT images in sequential order, much like movie frames.

PICT is the standard macintosh graphic file format for graphics that are cut or copied to the Clipboard and for drawings that won't be output on PostScript printers. This format is ideal for on-screen presentations, but page layout programs sometimes have problems with PICT files. Files are sometimes called metafiles because they can contain both bit maps and QuickDraw-based objects.

Picture element. Digital images are composed of touching pixels, each having a specific color or tone. The eye merges differently colored pixels into continuous tones.

Pixel Skipping
A means of reducing image resolution by simply deleting pixels throughout the image.

A software compression utility for the PC. It allows you to compress or "zip" a file or a number of files into one archive file in the ZIP file format.

Extends the capabilities of a web browser, allowing the browser to run multimedia files.

Photomultiplier tube. The light sensing device generally used in drum scanners.

A server using the Post Office Protocol, which holds users' incoming e-mail until they read or download it.

One of several rendezvous points where TCP/IP connections can be made on a computer. Ports are numbered, with several locations reserved for specific types of network activity, such as telnet on port 23, HTTP traffic on port 80 and USENET news (NNTP) on port 119.

The conversion of continuous tone data into a series of visible tonal steps or bands.

Pixels per inch or pixels per centimeter. Units of measurement for scanned images.

Point-to-Point Protocol. It provides a method for transmitting packets over serial point-to-point links.

Parameter RAM (pronounced pee-ram). A small portion of the Mac's RAM set aside to hold basic information such as the date and time, speaker volume, desktop pattern, and key-board and mouse settings. PRAM is powered by a battery, so it doesn't lose the settings when you shut down. Sometimes, however, the PRAM data gets corrupted, causing crashes or other problems.

Primary color
A base color that is used to compose the other colors.

Process Ink Colors
CMYK pigments used in printing processes, chosen to produce the widest range of color mixtures.

The color characteristics of an input or output device, used by a CMS to ensure color fidelity.

Information about an object, including settings or options for that object. For example, you look at properties of a file for information such as the file size, file type, and file attributes.

When data is being transmitted between two or more devices something needs to govern the controls that keep this data intact. A formal description of message formats and the rules two computers must follow to exchange those messages. Protocols can describe low-level details of machine-to-machine interfaces (e.g., the order in which bits and bytes are sent across wire) or high-level exchanges between application programs (e.g., the way in which two programs transfer a file across the Internet).

Proxy ARP
A technique in which one machine, usually a gateway, answers ARP requests for another machine. By pretending to be the physical network location of another machine, the gateway takes over the responsibility of routing packets destined for the other machine. For instance, a gateway can proxy ARP for addresses that the gateway identifies as being off the local network and that the gateway has a route for. The originating computer receives the gateway's proxy ARP reply and sends the datagram on to the gateway, which routes the datagram to its actual destination network.

Packet Switch Node; a store-and-forward packet switch (formerly called an IMP).

Software that has no copyright or fee, which means you can copy, use, and even alter and sell it.


Q or Return to Quick Index

Quality Factor
A multiplication factor (between 1 and 2) applied to output screen ruling to calculate scanning resolution for optimum output quality. This is also known as the halftoning factor.

Quarter Tones
Tones between shadow and midtones are known as 3/4 tones and those between highlight and midtones are known as 1/4 tones.

The process by which a web client requests specific information from a web server, based on a character string that is passed along.

A file extension for videos or "movies" (like animations) compressed using their QuickTime format.


R or Return to Quick Index

Random Access Memory. RAM is the most common type of computer memory, and it's where the computer stores system software, programs, and data you are currently using. It's formally called dynamic RAM (DRAM) because it's volatile, that is, the contents are lost when you turn off the computer (or crash). It's pronounced ram and measured in megabytes.

A synonym for grid. Sometimes used to refer to the grid of addressable positions in an output device.

Recorder element. The minimum distance between two recorded points (spots) in an imagesetter.

Remote system
Another computer on the Internet to which you connect. Interactions between computers are often described using the terms "local" and "remote" systems. The local system is your computer and the remote system is the other computer.

A term used to define image resolution instead of ppi. Res 12 indicates 12 pixels per millimeter.

An increase or reduction in the number of pixels in an imge, required to change its resolution without altering its size. See also down-sampling and interpolation.

In general, this refers to how sharp and clear an image looks on screen or on paper, and how much detail you can see. It's usually determined by the number of dots (or pixels) per square inch (the more there are, the higher the resolution) and is used to describe printers, monitors, and scanners.

Request For Comments; technical note series which began in 1969 describing DARPA and Internet research and development, particularly in the areas of protocol design and internetworking. Not all (in fact very few) RFCs describe Internet standards, but all Internet standards are written up as RFCs.

Red, green, and blue are the primary colors of light perceived by the eye.

Routing Information Protocol used by Berkeley UNIX systems to exchange routing information among a set of computers attached to a network. RIP packets are sent and received by a program called routed.

On-line catalog at UCSD for books and other material in the libraries at the University of California at San Diego.

Read-Only Memory. It's like software that's hard-wired into your computer - basic, permanent information that tells it things like how to load up the operating system when you turn it on.

A special purpose computer that attaches to two or more networks and routes packets from one network to the other. A router uses network layer addresses (such as IP Addresses) to determine if packets should be sent from one network to another. Routers send packets to other routers until they arrive at their final destination.

Rels (recorder elements) per inch. A measurement of the number of discrete steps that exposure units in imagesetting devices can make per inch.

Interface between Data Terminal Equipment (DTE) and Data Communications Equipment (DCE) employing Serial Binary Data Interchange, a standard set by the international standards organization - Consultative Committee on International Telegraphy and Telephony. The interface between a terminal to a modem for the transfer of serial data.

Rich Text Format. A file format for text files that includes formatting instructions. Also called Interchange Format.


S or Return to Quick Index

The process of converting analog data into digital data by taking a series of samples or readings at equal time intervals.

The extent to which one or two of the three RGB primaries predominate in a color. As quantities of RGB equalize, color becomes desaturated towards grey or white.

A device that converts images (such as photographs) into digital form so that they can be stored and manipulated on computers.

Screen Frequency
The number of rows or lines of dots in a halftone image within a given distance, normally stated in lines per inch (lpi) or lines per centimeter (lpm). A frequency of 200 lpi would only be used in high-quality printing.

Screen Ruling
Another term used for screen frequency.

Screen Saver
A moving picture or pattern that is displayed on the screen when no activity takes place for a specified period of time.

A type of program that consists of a set of instructions for another application or utility to use.

Scroll Bar
The bar that appears at the right side or the bottom of a window that contains more information that can be displayed. The scroll bar is used to scroll an object or parts of a document into view when the entire object or document does not fit in the window.

San Diego State University Network. The backbone network that connects multiple buildings on the SDSU campus.

Search Engines
A type of software that creates indexes of databases or Internet sites based on the titles of files, key words, or the full text of files.

Second Original
High-quality, contone reproduction of an image, intended to be identical to the original.

Secondary Color
Color obtained by mixing two primary colors. Although known as primary colorants, C,M, and Y are the secondary colors of light. Red plus green produce yellow, for example.

Serial Cable/Serial Port
A cable used to connect peripheral devices through a computer's serial port. Normally a 25-pin connector on each end, yet can be a 9-pin on one. A Serial Port can either be plugged into an expansion slot on the motherboard of your computer or built into the motherboard itself. Serial ports are used for such devices as printers, mice, and modems.

A computer that shares its resources, such as printers and files, with other computers on the network. An example of this is a Novell NetWare Server which shares its disk space with a workstation that does not have a disk drive of its own.

Service (NT service)
A process that performs a specific function in Windows NT and can be called by various other programs. Windows NT provides tools to monitor and administer services.

The darkest area of an image.

Software that you can try before you buy. It's distributed through on-line services, BBSs, and user groups. You're allowed to try it out and give copies to others, but if you want to keep using it, you must pay the registration fee.

A set of programs that allow Macromedia Director animation files to be played over the internet with a web browser.

Organization or facility where a host is located.

Through negotiations with a vendor, a renewable fee has been paid to allow a fixed number of copies of copyrighted software at one site.

Serial Line Internet Protocol. A protocol used to run IP over serial lines, such as telephone circuits or RS-232 cables, interconnecting two systems.

Simple Mail Transfer Protocol. Internet standard protocol for transferring electronic mail messages from one computer to another. SMTP specifies how two mail systems interact and the format of control messages they exchange to transfer mail.

Logical address of a communications access point to a specific device or program on a host.

Refers to the practice of blindly posting commercial messages or advertisements to a large number of unrelated and uninterested newsgroups.

Isolated light pixels in predominantly dark image areas, sometimes caused by incorrect readings or noise in the scanning device.

Spectral Highlight
A bright reflection from a light source containing little or no detail.

An extremely accurate color measurement device using a diffraction grating to split light into its components wavelengths, which are then measured by numerous light sensors.

A number-related document whereby calculations and formulas are applied to the data organized in rows and columns of cells.

Structured Query Language, a syntax used by many database systems to retrieve and modify information.

See Aliasing.

Start/Stop Bits
A start bit signals the start of a unit of data in asynchronous communications. A stop bit signals the stop of a unit of data. The unit can vary in length depending on the protocol.

Subnet Address
An extension of the Internet addressing system that allows a site to subdivide a single Internet address to cover multiple physical networks. This is done by dividing up the host address part of an IP Address into a local network number and host address number.

The base material used to carry out or support an image, for example, paper or film.

Subtractive Primaries
Another term for primary colorants.

The capture of more grey levels per color than is required for image manipulation or output. This additional data allows shadow details to be heightened, for example.
Syntax Error
Occurs when a user (or programmer) has put words in an order that a program does not understand.


T or Return to Quick Index

An AT&T term for a digital carrier facility used to transmit a DS-1 formatted digital signal at 1.544 megabits per second.

A term for a digital carrier facility used to transmit
Formatting codes used in HTML documents. These tags indicate how the parts of a document will appear when displayed by a Web client program.

An area that runs across the bottom (usually) of the Windows 95 desktop. Running applications are represented as buttons on the taskbar, the current window is shown as a depressed button, all other applications are displayed as raised buttons.

Transmission Control Protocol. This is a transport layer protocol that establishes a reliable, full duplex, data delivery service used by many TCP/IP application programs. The TCP software uses the IP protocol to transmit information across the Internet.

Transmission Control Protocol/Internet Protocol. A set of protocols, resulting from ARPA efforts, used by the Internet to support services such as remote login (TELNET), file transfer (FTP) and mail (SMTP).

The Internet standard protocol for remote login (terminal connection) service. TELNET allows a user at one site to interact with a remote timesharing system at another site as if the user's terminal were connected directly to the remote computer.

Communication device that lets a user send information to a computer by typing on a keyboard, and prints responses from the computer on paper or a screen.

Terminal Mode
Many communications programs allow you to mimic a computer terminal, which is basically a keyboard and CRT display and/or a printer. A common terminal mode emulator is VT-100.

Terminal Ready (TR)
This light is illuminated when your computer has turned on the RS-232 (serial) interface. Sometimes this light will not come on until you have loaded your communications software into memory.

Terminal Server
A small, specialized, networked computer that connects many terminals to a LAN through one network connection. A terminal server can also connect network users to asynchronous ports or a host.

Thermal Wax Transfer
A printing process using small heating elements to melt dots of wax pigment on a carrier film, which are then transferred to paper or transparent film by contact. This differs from the dye sublimation process in that individual dots do not fuse together, so thermal wax transfer appears to be of a lower resolution.

In the context of Windows NT, a thread is sometimes used to refer to an NT service. Threading also refers to a low-level system architecture concept used in some multitasking operating systems.

The point at which an action begins or changes. The threshold setting used in scanning line art determines which pixels are converted to black and which will become white. The threshold defined in the USM process determines how large a tonal contrast must be before sharpening will be applied to it.

Tag Image File Format. A graphic file format, TIFF files are also bit maps, but they can be any size, resolution, or color depth. It is the most versatile, reliable, and widely supported bit-mapped format and is the standard format for saving scanned images. However, the format does have several variations which means that occasionally an application may have trouble opening a TIFF file created by another program.

Title bar
The horizontal bar at the top of a window. The title bar shows the name of the window.

Tone Curves
Also known as gamma curves. These are used to smoothly adjust the overall tonal range of an image, or the individual tonal ranges of each color channel.

A collection of buttons that typically make the more common tools for an application easily accessible.

Terminate and Stay Resident.


U or Return to Quick Index

Unsharp masking. A process used to sharpen images.

UNIX-to-UNIX Copy Program. This was initially a program run under the UNIX operating system that allowed one UNIX system to send files to another UNIX system via dial-up phone lines. Today, the term is more commonly used to describe the large international network which uses the UUCP protocol to pass news and electronic mail.

A database of book reviews, magazines, and articles, including FAX article delivery. It provides table of contents information for over 14,000 journals in all disciplines held by the libraries in the Colorado Academic and Research Libraries consortium and provides on-line access to ERIC, at education database. Coverage for most journals begins with 1989.

A version of the UNIX operating system adapted for CRAY computers.

An operating system developed by Bell Laboratories that supports multiuser and multitasking operations.

Send a file to another computer using a modem.

Uninterruptible Power Supply. A unit that switches to battery power whenever the power cuts out.

Uniform Resource Identifier, a string of characters that represents the location or address of a resource on the Internet and how that resource should be accessed. A URI is a superset of the Uniform Resource Locator.

Uniform Resource Locator, a string of characters that represents the location or address of a resource on the Internet and how that resource should be accessed. World Wide Web pages are assigned a unique URL. Each hyperlink on a web page contains the URL of the page to be linked to. is the URL for this page.

A network of newsgroups. There are thousands of newsgroups available through USENET. Each one covers a specific topic or subject area.

User Id
The string of characters that identifies you. The name by which you are known to the network. Also known as username.

UNIX-to-UNIX Copy Program, a program that lets you copy files between UNIX systems. UUCP protocols are used to transfer news and Email messages through USENET.


V or Return to Quick Index

Very East Rodent-Oriented Net-wide Index to Computerized Archies. An index searcher of Gopher repositories. Searches are based on keyword criteria to help users find Gopher-based information without doing a menu-by-menu, site-by-site search.

A 12-inch disk that's similar to an audio CD but holds visual images (such as high-quality movies) as well as music. Also called a laserdisc.

A program that replicates itself from one file or disk to another without your consent. They are spread through floppy disks, networks, and on-line services and can go undetected (unless you have an antiviral utility) until something goes wrong. Some viruses deliberately destroy data, and even those designed to be benign can cause crashes, slowdowns, and file corruption.

Digital Equipment Corporation proprietary operating system which runs on the VAX series of machines.

Video On Demand.

Video RAM. A type of memory dedicated to handling the image displayed on a monitor. VRAM is built into many Macs, and it also comes on display cards.


W or Return to Quick Index

Wide Area Information Server. WAIS is best at searches for various sources of academic information that has been indexed based on content. Its indexes consist of every word in a document and each word carries the same weight in a search.

A graphical pattern displayed on the desktop.

Web browser
Also known as a Web client program, this software allows you to access and view HTML documents. Netscape, Mosaic, Lynx, WinWeb, and MacWeb are some examples of Web browsers.

Web page
A document created with HTML that is part of a group of hypertext documents or resources available on the World Wide Web.

Web walking
Using a Web client program to move through the documents available on the World Wide Web. This casual browsing nature of navigating the WWW has also been referred to as strolling, crawling and jumping.

A person or group of people who maintain and administer a web server. Webmaster also refers to a standard Email address at most web hosts where comments and questions can be sent.

White Point
A movable reference point that defines the lightest area in an image, causing all other areas to be adjusted accordingly.

An Internet program which allows users to query databases of people and other Internet entities, such as domains, networks, and hosts. The information for people generally shows a person's company name, address, phone number and email address.

Wide Area Network (WAN)
Network spanning multiple geographic distances, usually connected by telephone lines, microwave, or satellite links.

A character (usually * or ?) that can stand for one or more unknown characters during a search.

Microsoft software that adds a Mac-like graphical user interface to IBM PCs and compatibles.

Word Processing
Entering, editing and formatting text with the use of spelling checkers, outlining, tables, footnotes, and tables of contents.

A networked personal computing device with more power than a standard IBM PC or Macintosh. Typically, a workstation has an operating system such as UNIX that is capable of running several tasks at the same time. It has several megabytes of memory and a large high-resolution display.

World Wide Web or W3 is the hypermedia document presentation system that can be accessed over the Internet using software called a Web browser.

What you see is what you get. The image you see on the screen matches what will print on paper. Pronounced wizzy-wig.


X or Return to Quick Index

A data communications interface specification developed to describe how data passes into and out of public data communications networks. The CCITT and ISO approved protocol suite defines protocol layers 1 through 3.


Z or Return to Quick Index

Compressed version of a program or document.

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