ROHAN Academic Computing

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 webmaster@rohan.sdsu.edu for inclusion consideration.

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EARN

European Academic Research Network.

Echo (Local, Remote)

Local echo ON causes all transmitted data to be sent to the screen of the sending computer. Remote echo ON causes everything that the remote computer (the one you are communicating with) transmits to be duplicated on your computer's screen. See Duplex.

EBCDIC

Extended Binary-Coded Decimal Interchange Code. A standard character-to-number encoding used primarily by IBM computer systems. See ASCII.

E-mail

Electronic Mail. Private messages sent between users on different computers, either over a network or via a modem connection to an on-line service or BBS.

Encoding

File transfer formatting that enables encrypted, compressed or binary files to be transferred without corruption or loss of data.

Encryption

A way of coding information in a file or e-mail message so that if it is intercepted by a third party as it travels over a network it cannot be read.

EPS

Encapsulated PostScript. An EPS file usually has two parts: a PostScript (text) description that tells a PostScript printer how to output the resolution-independent image, and (optionally) a bit-mapped PICT image for on-screen previews. (EPS files without a PICT preview is usually displayed as a gray rectangle.) EPS files generally can't be edited, even by the program that created them (Illustrator files are exceptions).

EPS 5

Another term used for DCS.

ERIC

An index to educational journal articles and documents collected by national clearing houses for educational information. It provides summaries of the articles and documents, and contains citations back to 1966.

Ethernet

An IEEE 802.3 standard data link layer which can operate over several different media including fiber optic, coaxial cable and twisted-pair cable. This 10 million-bit-per-second networking scheme is widely used on campus because it can network a wide variety of computers; it is not proprietary; and components are widely available from many commercial sources.

Executable File

Refers to a file that is a program. Executables in DOS and Windows usually have an .exe or a .com extension. In UNIX and Macintosh environments, executable files can have any name.

External viewer

Program used for presenting graphics, audio and movies while browsing World Wide Web pages via a Web client program. Helper applications is another term for these external programs.

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FAQ

Frequently Asked Questions. A document that covers a topic of general concern to many users. FAQs are a good way for new users to get information on various aspects of the Internet.

FDDI

Fiber Distributed Data Interface. An emerging standard for network technology based on fiber optics that has been established by the American National Standards Institute (ANSI). FDDI specifies a 100-million bit per second data rate.

File

A collection of information on a disk, usually a document or a program, that's lumped together and called by one name.

File Permissions

When you place files on a UNIX system you can assign the files various levels of permission, specifying who can access them, and what type of access they can have.

File Server

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.

Film Recorder

Used in reference to color transparency recording devices, and sometimes also to imagesetters.

Filter

A piece of software that an application uses for file-format conversion or special effects. PageMaker, for example, has a filter that lets it import Microsoft Word files, while Photoshop has dozens of filters for special effects (such as image blurring). Filters can be part of the main application or external programs called plug-ins.

Finger

A program that displays information about someone on the internet.

Firewall

A mechanism that isolates a network from the rest of the Internet, permitting only specific traffic to pass in and out.

Flaming/Flame War

Reacting to someone's newsgroup posting or e-mail in a hostile manner by publicly chastising the person or bombarding the person with nasty e-mail.

Flatbed Scanner

Any scanning device that incorporates a flat transparent plate, on which original images are placed for scanning. The scanning process is linear rather than rotational.

Floating-point Processor

A special chip that handles sophisticated calculations, such as those used in spreadsheets, CAD, and scientific programs.

Folder

An object that can hold other objects, such as other folders and files.

Font

The software that creates a typeface on a computer screen.

Format

To initialize a disk to prepare it for use. The disk is checked for errors and organized so that data can be recorded and retrieved. Formatting a used disk erases any previously stored information.

FPO

For Position Only. A low resolution image placed in a document to indicate where the final version is to be positioned.

Fragmentation

A condition where parts of a file are stored in different locations on a disk. When a file is fragmented, the drive's read/write head has to jump from place to place to read the data; if many files are fragmented, it can slow the drive's performance.

Frame-grabbing System

A combination of hardware and software, designed to capture individual frames from video clips for further digital manipulation, or consecutive replay on computer platforms.

FTP

File Transfer Protocol. The Internet standard high-level protocol for transferring files from one computer to another across the network.

FTP site

A computer which stores files that can be retrieved using FTP. FTP sites which allow anyone to retrieve files (without having an account on that computer) are known as Anonymous FTP sites.

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Gamma

The curve that describes how the middle tones of your images appear. Often incorrectly referred to as "brightness" and/or "contrast", gamma is a non-linear function. Changing the value of the gamma affects middle tones while leaving the white and black of the image alone. Used to compensate for differences between Macintosh and PC monitors.

Gamma Correction

The correction of tonal ranges in an image, normally by the adjustment of tone curves.

Gamut

The limited range of colors provided by a specific input device, output device or pigment set.

Gang Scanning

Sequential scanning of multiple originals using the same previously defined exposure setting for each.

Gateway

A special-purpose dedicated computer that attaches to two or more disparate networks and converts data packets from one form to another.

GB

Gigabyte. A unit of data storage size which represents 10^9 (one billion) characters of information.

Gb

Gigabit. 10^9 bits of information (usually used to express a data transfer rate; as in, 1 Gigabit/second = 1Gbps).

GCG (Grey Component Replacement)

A technique for replacing all the neutral tones of an image with an appropriate amount of black.

GIF

Graphic Interchange Format (pronounced jiff). A file compression format developed by CompuServe for transferring graphic files to and from on-line services.

Gigabyte

1,024 megabytes, or 1,048,576 kilobytes of digital data.

gopher

A consistent user interface and gateway into many on-line white pages and other address databases.

Graphical User Interface (GUI)

The graphical visual representation of the working environment that presents the elements of your computer as objects on a desktop.

Grey Balance

The balance between CMY colorants required to produce neutral greys without a color cast.

Grey Levels

Discrete tonal steps in a continuous tone image, inherent to digital data. Most CT images will contain 256 grey levels per color.

Greyscale

A continuous tone image comprising black, white, and grey data only.

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Hacker

Slang term for a technically sophisticated computer user who enjoys exploring computer systems and programs, sometimes to the point of obsession.

Halftone

A simulation of continuous tones by the use of black or overlapping process color dots of varying size or position.

Halftoning Factor

See quality factor.

Halo

A light line around object edges in an image, produced by the USM (sharpening) technique.

Handle

Unique character string identifier assigned to each entry in the NIC WHOIS database.

Handshaking

The process computers and modems go through in order to establish a connection and agree on the speed and protocols for data transmission.

Hayes Compatible

A modem is considered Hayes Compatible if it supports the Hayes command set (a language used to communicate with and control a modem).

Header

The portion of a packet, preceding the actual data, containing source and destination addresses, error checking and other fields. A header is also the part of an electronic mail message that precedes the body of a message and contains, among other things, the message originator, date and time.

High Key

A light image that is intentionally lacking in shadow detail.

Highlight

The lightest tones in an image. A spectral highlight is a bright, reflected light source.

Histogram

A chart displaying the tonal ranges present in an image as a series of vertical bars.

Home Page

The document that is displayed when you first open a web client program. Also, commonly used to refer to the first document you come to in a collection of documents on a Web site.

Host

The main computer system to which users are connected.

Hostname

Name which officially identifies each computer attached to the Internet.

Hotlist

A file containing lists of Internet Web pages, enabling you to easily access your favorite Web pages.

HP

Hewlett Packard.

HTML

HyperText Markup Language. A system for tagging various parts of a Web document that tells the Web client programs how to display the document's text, links, graphics and attached media.

Hue

The color of an object perceived by the eye due to the fact that a single or pair of RGB primary colors predominates.

Hypermedia

Describes hypertext in which various types of data can be stored - sound, images, video and so on - as regular text.

Hypertext

A text-linking strategy that lets you jump between related information in a document by clicking on a button or highlighted word. On-line help systems often use hypertext links, as do some programs designed for the electronic distribution of documents.

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I/O

Input/Output.

I-beam

The blinking vertical line that shows the point at which text or graphics will be inserted.

IBM

International Business Machines Corporation.

Icon

A graphic symbol, usually representing a file, folder, disk or tool.

Image Map

A graphic divided into regions or "hotspots". When a particular region is clicked, it calls up a web page that has been associated with that particular region.

Imagesetter

A device used to record digital data (images and text) onto monochrome film or offset litho printing plates by means of a single or multiple intermittent light beams. Color separated data is recorded as a series of slightly overlapping spots to produce either solid areas of line-art or halftone dots for printing continuous tones.

Import

To bring data into a document from another document, often generated by a different application.

Inactive Window

A window that is open but is not the top window.

Infopath

Internet gopher for the University of California at San Diego.

Information Technology

Includes matters concerned with the furtherance of computer science and technology, design, development, installation and implementation of information systems and applications.

Initializing (formatting)

Setting up a disk (any kind) to receive information. When a disk is initialized (formatted), its magnetic media is divided into tracks and sectors, and structure files that your computer uses to keep track of data are created.

Inline images

Graphics that are contained within a document's textual information. In a Web document, these graphics can either be loaded automatically when the page is accessed or loaded manually by clicking on the image's icon.

Installer

A utility that copies system software or an application from floppy disks or a CD-ROM to your hard disk. An Installer may also decompress the new files, remove obsolete files, place extensions and control panels in their proper folders, and/or create new folders.

Interface

The way a computer interacts with a user or a peripheral.

Internet

The Internet (note the capital I) is the largest internet in the world. It is a three level hierarchy composed of backbone networks (e.g., NSFNET, MILNET), mid-level networks, and stub networks. The Internet is a multiprotocol internet.

Interpolation

In the image manipulation context, this is the increase of image resolution by the addition of new pixels throughout the image, the colors of which are based on neighboring pixels.

Interrupt

A brief interruption of the computer's activity so that an urgent task can be performed.

IP

Internet Protocol is the standard that allows dissimilar hosts to connect to each other through the Internet. This protocol defines the IP datagram as the basic unit of information sent over the Internet. The IP datagram consists of an IP header followed by a message.

IP Address

Network addresses are usually of two types: (1) the physical or hardware address of a network interface card; for Ethernet this 48-bit address might be 0260.8C00.7666. The hardware address is used to forward packets within a physical network. (2) The logical or IP Address is used to facilitate moving data between physical networks and is made up of a network number, a subnetwork number, and a host number. All Internet addresses at SDSU have a network number of 130.191, a subnet number in the range of 1-254, and a host number in the range of 1-254.

IP Datagram

The basic unit of information passed across the Internet. An IP Datagram is to the Internet as a hardware packet is to a physical network. It contains a source and destination address along with data. Large messages are broken down into a sequence of IP Datagrams.

IRC

Internet Relay Chat. A program that allows you to carry on "live" conversations with people all over the world by typing messages back and forth across the Internet.

ISAAC

Information System for Advanced Academic Computing. Serves as a clearinghouse for information about the use of IBM-compatible hardware and software as aids to instruction and research in higher education. Membership is free to all students, faculty, and staff at these institutions.

ISO

International Organization for Standardization, the group that developed the OSI protocols.

ISP

Internet Service Provider. A company that provides access to the Internet. A service provider can offer simple dial-up access, SLIP/PPP access, or a dedicated line.

IT8

Industry standard color reference target used to calibrate input and output devices.

ITV

Interactive Television.

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Jaggies

See aliasing.

Java

An object-oriented programming language to create executable content (i.e. self-running applications) that can be easily distributed through networks like the Web.

JPEG

Joint Photographic Experts Group is a graphic file format that has a sophisticated technique for compressing full-color bit mapped graphics, such as photographs.

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KB

KiloByte. A unit of data storage size which represents 10^3 (one thousand) characters of information.

Kb

Kilobit. 10^3 bits of information (usually used to express a data transfer rate; as in, 1 Kilobit/second = 1Kbps = 1Kb).

Kermit

An error-checking file-transfer protocol used to copy files from one computer to another. Also the name given to the public domain software distributed by Columbia University, which supports this protocol.

Kernel Size

The number of pixels sampled as a unit during image manipulation and sharpening processes.

Keyword

Specified words used in text search engines.

Kilobyte (Kb)

1,024 bytes of digital data.

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LAN

Local Area Network. A network of directly-connected machines (located in close proximity), providing high speed communication over physical media such as fiber optics, coaxial cable, or twisted pair wiring.

Laser Printer

Although a number of devices employ laser technology to print images, this normally refers to black-and-white desktop printers, which use the dry toner, xerographic printing process.

Laserdisc

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 videodisc.

Links

Synonymous with anchors, hotlinks and hyperlinks.

Line Art

Images containing only black and white pixels. Also known as bilevel images. The term line art is sometimes used to describe drawings containing flat colors without tonal variation.

LION

Library Internet Online Network. A menued front-end system at SDSU that allows access to a number of databases such as library on-line catalogs, periodical indexes, and Internet gophers.

LISTSERV

A distribution list management package whose primary function is to operate mailing lists. It allows groups of computer users with a common interest to communicate among themselves.

Local system

The system you are using. Interactions between your computer and another computer on the Internet are sometimes described using the terms "local" and "remote" systems. The local system is your computer and the remote system is the other computer.

LOCIS

Library of Congress catalog system. The Library of Congress has an extensive and useful congressional legislation system that you can use to look up the bills that are in Congress, as well as having nearly any book ever published in the United States.

Login

The account name used to access a computer system.

Lossy

Image compression that functions by removing minor tonal and/or color variations, causing visible loss of detail at high compression ratios.

Low Key

A dark image that is intentionally lacking in highlight detail.

LPI/LPCM

Lines per inch or per centimeter. Units of measurement for screen ruling.

Lurker

Slang term for someone who regularly reads newsgroup, BBS, or mailing list discussions, but rarely participates in them.

Lynx

A type of browser designed to work with text-only Internet connections like dial-up UNIX shell accounts.

LZW

The Lempel-Ziv-Welch image compression technique.

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Mail Merge

The merging of database information (such as names and addresses) with a letter template in a word processor, in order to create personalized letters.

Mailing List

A list of Email users who are members of a group. A mailing list can be an informal group of people who share Email with one another, or it can be a more formal LISTSERV group which discusses a specific topic.

Mainframe

A large, multi-tasking computer that is used by many users.

Marvel

Machine-Assisted Realization of the Virtual Electronic Library. The Library of Congress' gopher. It presents information about the Library of Congress such as facilities and services, reading rooms, copyright, services to libraries and publishers, etc., as well as other Internet resources.

Math Coprocessor

Another name for a floating-point processor.

Matrix

This often refers to a 2-dimensional array of CCD elements.

Medium

The material used to support the transmission of data. Examples include twisted-pair wire, coaxial cable, optical fiber, or electromagnetic wave (microwave).

Megabit (Mb)

Megabit. 10^6 bits of information (usually used to express a data transfer rate; as in, 1 Megabit/second = 1Mbps).

Megabyte (MB)

MegaByte. A unit of data storage size which represents 10^6 (one million) characters of information.

Megahertz (MHz)

A million cycles (occurrences, alterations, pulses) per second. Used to describe the speed at which a computer's processor (or CPU) operates.

Melvyl

An on-line catalog system containing books, music scores and recordings, audiovisual materials, maps, and computer files from UC libraries and the California State Library. Also featured are periodicals from several sources.

Memory

In general, another word for dynamic RAM, the chips where the computers store system software, programs, and data you are currently using. Other kinds of computer memory you may encounter are parameter RAM (PRAM), video RAM (VRAM), and static RAM (SRAM). Most computer memory is volatile, that is, its contents are lost when the computer shuts down.

Menu

A list of commands.

Menu Bar

The horizontal bar that contains the names of available menus. The menu bar is located below the title bar.

Message

A collection of data that is ordered according to the rules of a given protocol suite, such that it is intelligible to the sending and receiving software.

MHz

Megahertz. A million cycles (occurrences, alterations, pulses) per second. Used to describe the speed at which a computer's processor (or CPU) operates. A 25-MHz processor can handle 25 million operations per second.

MIDI

Musical Instrument Digital Interface. A technology that enables a computer to record and play musical performance.

Midtone

The middle range of tones in an image.

MILNET

Military Network. A network used for unclassified military production applications. It is part of the DDN and the Internet.

MIME

Multi-purpose Internet Mail Extensions. A format originally developed for attaching sounds, images and other media files to electronic mail, but now also used with World Wide Web applications.

MIME mappings

A list of file extensions and the types of files they belong to. When the server sends an HTTP reply, it sends a type/subtype header according to the requested file's extension.

MIME type/subtype

An HTTP header sent with a reply that determines how a client will view or use the message. The MIME type tells the general type of document, such as image or application, and the subtype tells the specific type such as GIF or ZIP.

MIPS

Millions of Instructions Per Second.

Mirror site

An FTP site that is created after the contents of an original FTP archive server are copied to it. Usually, mirror sites use larger and faster systems than the original, so it's easier to obtain material from the mirror. Mirror sites are usually updated daily, so everything on the original is also at the mirrors. Tip - Always use the mirror site that is physically closest to you.

Modem

A device which converts digital signals into analog signals (and back) for transmission over telephone lines (modulator and demodulator).

Moire

A repetitive interference pattern caused by overlapping symmetrical grids of dots or lines having differing pitch or angle.

Monochrome

Single-colored. An image or medium displaying only black-and-white or greyscale information. Greyscale information displayed in one color is also monochrome.

Motherboard

The heart, soul, and brains of a computer. This plastic board resembles a miniature city, but its buildings are actually chips for things like the processing, RAM, and ROM, and the tiny roads connecting them are circuit traces. Also called the logic board. There are no fatherboards or sonboards, but see daughterboard.

Mottling

A texture similar to orange peel sometimes caused by sharpening. It is particularly visible in flat areas such as sky or skin.

MOV

A file extension found on the World Wide Web that denotes that the file is a movie or video in QuickTime format.

MPEG

Moving Pictures Expert Group. MPEG is an international standard for video compression and desktop movie presentation. You need a special viewing application to run the MPEG movies on your computer. MPEG II is a newer standard for broadcast-quality video.

Multimedia

Any presentation or software program that combines several media, such as graphics, sound, video, animation, and/or text.

Multiplex

The division of a single transmission medium into multiple logical channels supporting many apparently simultaneous sessions.

Multitasking

The capability of an operating system to handle multiple processing tasks, apparently, at the same time.

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