Computer-related Terms: Glossary and Definitions

A

access

The reading or writing of data; as a verb, to gain entry to data. Most commonly used in connection with information access, via a user ID, and qualified by an indication as to the kinds of access that are permitted. For example, read-only access means that the contents of the file may be read but not altered or erased.

Access Control List

(ACL) A list of the services available on a server, each with a list of the hosts permitted to use the service.

access time

The time interval between the instant that data is requested and the instant that it is received.

account

Your subscription to a networked computer system.

account name

Same as your login ID or user ID. The word you type at the "Login:" prompt; your electronic name.

address

A character or group of characters that identify a register, a location or some other data source or destination.

aggregate

n. A total created from smaller units. For instance, the population of a county is an aggregate of the populations of the cities, rural areas, etc. that comprise the county.
v. To total data from smaller units into a large unit. Example: "The Census Bureau aggregates data to preserve the confidentiality of individuals."

aggregate data

Data that have been aggregated.

algorithm

A set of rules for solving a problem in a given number of steps.

alias

See nickname.

analog

A method of storing information, used by most audiotapes, videotapes and laserdiscs (and all LP phonograph records, remember those?). An analog device uses a physical quantity, such as length or voltage, to represent the value of a number. By contrast, digital storage relies on a coding system of numeric units.

Application Layer

Layer seven of the OSI reference model. It serves as a means by which applications access communications services.

application

The use to which a data processing system is put within a given discipline, such as a payroll application, an airline reservation application or a network application.

application program

A program that is written for or by a user that applies to the users discipline.

application software

A group of programs designed to perform tasks that can be tailored to a users specific needs.

archive

v. To copy programs and data onto an auxiliary storage medium (disk, tape,etc.) for long-term retention, such as when disk space has become full. 
n. A file with a structure that allows storage of multiple files within it in such a way that the names of the files can be listed and files can be individually added and deleted. The terminology is typically associated with microcomputers. On a mainframe, such a file is typically called a library.

argument

A value supplied to a procedure, macro, subroutine, or command that is required in order to evaluate that procedure, macro, subroutine, or command. Synonymous with parameter.

ASCII

American Standard Code for Information Interchange (pronounced ask-ee). The form in which text characters are handled in most computer systems and networks. ASCII text has no special characters for formatting such as underlined or bold characters, font changes, etc., thus can be viewed on any personal computer or terminal.

assembler

A program that converts symbolically-coded programs into object level, machine code. In an assembler program, unlike a compiler, there is a one-to-one correspondence between human-readable instructions and the machine-language code.

ATM

Asynchronous Transfer Mode. A standard for cell relay that uses fixed length cells of 53 bytes, 5 bytes of which are headers. Can support multiple services including voice, video and data.

ATM Forum

An industry-wide effort that is now an international consortium of more than 400 companies who define ATM interoperability specifications and promote industry-wide cooperation to help proliferate ATM and thus drive implementation costs down.

audit

A personal or computerized review process that accounts for the adequacy, effectiveness, security and overall functionality of a data activity.

authentication

Process of establishing who you are.

authorization

Permission to access non-public information or use equipment that is either fully or partially restricted. Process of establishing what you can do.

autonomous system

A collection of one or more networks that are administrated by the same entity. Each regional network (such as SURAnet) is an autonomous system.

B

backbone

Refers to a piece of cable used to connect different floors or departments together into a network. Also generalized to a network that connects networks together.

background processing

Users may use a terminal for one project and concurrently submit a job that is placed in a background queue that the computer will run as resources become available. Also refers to any processing in which a job runs without being connected to a terminal.

backspace

A keyboard operation that moves the cursor one place to the left. A destructive backspace erases characters as it goes, thus allowing users to modify what has been typed (distinguished from the left- arrow key).

backup

n. A resource that is or can be used as a substitute when a primary resource fails or when a file has been corrupted.
v. To save as in to make a copy in case of future failure or corruption.

bandwidth

A piece of the spectrum occupied by some form of signal, where it is television, voice, fax data, etc.. Signals require a certain size and location of bandwidth in order to be transmitted. The higher the bandwidth, the faster the signal transmission, and thus allowing for a more complex signal such as audio or video. Because bandwidth is a limited space, when one user is occupying it, others must wait their turn. Bombarding the Internet with unnecessary information is referred to as "taking up bandwidth."

baseband

A network medium that uses only one carrier frequency. Examples are Ethernet and PhoneNet.

BASIC

Beginners All-purpose Symbolic Instruction Code. A commonly used personal-computer language, first developed at Dartmouth during the 1960s.

batch processing

Originally, a method of organizing work for a computer system, designed to reduce overhead by grouping similar jobs. In one scheme, jobs were collected into batches, each requiring a particular compiler. The compiler was loaded, and the jobs submitted in sequence to the compiler. The term has come to be applied to background processing of jobs not requiring user intervention on multiuser systems. See compiler.

batch query

A query that has been saved so that it can be used more than once and run in the background.

binary

A file containing one or more strings of data bits which are not printable characters. Some binary files may be computer programs or other forms of data that contain no text characters at all. Binary files cannot be displayed on screen, but can be downloaded for use with appropriate applications on your computer. Binary (base 2) is also the building block of computer information, representing "on" or "off" and "true" or "not true" as 1 or 0.

binary number

A number written using binary notation which only uses zeros and ones. Example: decimal number seven in binary notation is: 111.

bit

A binary digit, either a 0 or 1. In the U. S. , 8 bits make up one byte; in Europe, byte equals one word.

bitmapped terminal

A terminal that can turn individual screen dots on or off.

BITNET

Because Its Time NETwork. Started in 1981 by City College of New York and Yale University, it is a network linking hosts at educational and research institutions in the United States, Canada, Europe and other countries using the RSCS protocols. Merged with CSNet to form CREN.

bits per second (bps)

The speed at which bits are transmitted.

block

A sequence of words or characters written contiguously, such as into a group, by a computer and stored on a disk, diskette, magnetic tape, etc.

bold

A way of emphasizing a word of text, as in darker type or brighter characters on a video display terminal.

booting

Turning on your computer.

break

An interruption to a transmission; usually a provision to allow a controlled terminal to interrupt the controlling computer.

bridge

A device that connects two networks and passes traffic between them based only on the node address, so that traffic between nodes on one network does not appear on the other network. For example, an Ethernet bridge only looks at the Ethernet address.

broadband

A communications medium on which multiple signals are simultaneously transmitted at different frequencies. Also refers to switching capability implemented on this medium that allows communication between devices connected to it. In telecommunications it is defined as any channel with a bandwidth greater than voice grade (4 KHz).

broadcast

A single message addressed to all nodes on a network.

browser

A software tool used to read electronic documents. Mosaic, NetScape and Lynx are the most popular browsers.

buffer

A temporary memory for data, normally used to accommodate the difference in the rate at which two devices can handle data during a transfer.

bug

An error. Can be a hardware malfunction or a software programming error.

bulletin board (BBS)

A computer system which can be called using a modem.

BUS topology

Network wiring commonly used by Ethernet in which all nodes on the network see all packets.

byte

A group of adjacent binary digits, usually 8, on which a computer operates as a unit; often used to represent a single character. (See bit. )

C

cable

A set of wires connecting pieces of computer hardware.

carriage return

The or key on your keyboard. On-line commands often must be followed by .

CD-ROM

Compact Disk - Read Only Memory. Optical (CD) disks that are mastered and then can only be read; i.e., the data cannot be manipulated, removed, etc.

cell relay

Packet-switching using small, fixed-sized packets called cells. The fixed size allows for very high speed switching. It is the basis for SMDS and ATM.

channel

Any medium by which information can be transmitted. For example, the air is a channel for our voices just as much as a fiber optic line can be data for a video signal.

character

Any symbol (usually alphabetic, numeric, or punctuation) that can be entered into your computer.

character set

A set of characters handled by a specified machine; sets include alphabetic characters, numbers, symbols, graphics characters, a space character and control characters. Graphics characters denote a printed mark; control characters produce some particular effect. Two of the most widely used sets are ASCII and EBCDIC.

chip

A tiny piece of semi-conductive material, usually based on silicon, used in the manufacture of electronic components.

client

A computer program that uses the services of another computer program. Software that extracts information from a server; your auto-dial phone is a client, and the phone company is its server.

client/server

A relationship in which client software obtains services from a server on behalf of a person.

Client-Server Interface

An architecture that provides for the splitting of user requests (usually called clients) and a related server function, most commonly across a network. The combined effect is to provide the clients with access to some service such as databases, printing, etc.

COBOL

COmmon Business Oriented Language The first standardized computer language. At Emory it is most commonly used for administrative applications.

code

n. A language for expressing operations to be performed by a computer.
v. To write in such a language.

collision

The result of two nodes transmitting at the same time on a multiple access network such as Ethernet. Both packets may be lost or partial packets may result.

column

A vertical arrangement of characters or other expressions.

command

A request, typed from a terminal or embedded in a file, to perform an operation or to execute a particular program.

communications line

A physical medium (wire, microwave beam) used to transmit data.

communications program

A program that makes a computer act as a terminal to another computer. Communications programs usually provide for file transfer between microcomputers and mainframes.

compiler

A program that translates human-readable programs into a form the computer understands. The input (source code) to the compiler is a description of an algorithm in a problem- oriented language; its output (object code) is an equivalent description of the algorithm in a machine-oriented language.

computer

A device or system that is capable of carrying out a sequence of operations in a distinctly and explicitly defined manner. The operations are frequently numeric computations or data manipulations, but also include data input and output. The ability to branch within sequences is its key feature.

concentrator

A device that brings together at a common center connections to a particular kind of network (such as Ethernet), and implements that network internally.

conference

An electronic meeting place dedicated to a particular subject where users come to participate in discussions or group projects. Conferences can be used to post a variety of information such as news services, newsletters, and statistics; also called "newsgroups," "bulletin boards," or "echoes." An electronic conference provides a many-to-many communication medium, as opposed to the person-to-person nature of e-mail. All conferences have a particular subject or purpose, and the topics and responses they contain might provide items of news, ideas, questions, or other information in almost any form. Some special-purpose conferences may have restricted access, allowing some users to write messages, some only to read, and some neither. The person responsible for the technical maintenance and/or community communication is called the "conference facilitator."

configuration

The particular hardware elements and their interaction in a computer system for a particular period of operation.

connect time

Time that elapses while the user of a terminal is connected to a time-sharing system; it is measured by the duration between logon and logoff.

control character

One of 32 characters of the ASCII character set that defines a control function for a character entry and display device such as a terminal. Examples are carriage return, tab, form feed and bell.

control key

A special function key on a computer keyboard, frequently used in combination with alphabetic keys, to enter commands.

copy

A function that reads data from a source, leaving the source data unchanged and writes it elsewhere. One example would be to copy a deck of punched cards onto magnetic tape.

CPU

Central Processing Unit. The main internal component of a computer where executions of instructions are carried out and calculations are performed.

crash

A computer system is said to crash when it stops working for some reason and must be restarted.

cursor

A symbol on a display screen that indicates the position at which the next character entered will be displayed. The symbol often blinks so that it can be easily noticed.

cursor control

The keyboard keys used to position the cursor on a display screen. They are usually keys labeled with arrows indicating the direction of movement.

Cyberspace

The nebulous "place" where humans interact over computer networks (the Internet is considered Cyberspace). Coined by William Gibson in Neuromancer.

D

Data Link Layer

Layer two of the OSI reference model. It controls the transfer of information between nodes over the Physical Layer.

data

Information suitable for communication, interpretation or processing by a computer.

data communications

The collection and redistribution of data through communications channels, often including operations such as coding, decoding and validation.

data entry

The entry of data into a computer or onto a computer-readable medium by an operator from a single data device, such as a card reader or keyboard.

data processing

The systematic performance of operations upon data, for example, handling, merging, sorting and computing.

Dataset

A file or group of files associated with one part of a study.

database

A collection of interrelated data values that may be integrated permanently into a single connected structure or integrated temporarily for each interrogation, known as a query. In its most technical sense, database implies that any of the data may be used as a key for specific queries. In more common usage it means any accessible collection of information and that only a limited set of data values may be used to specify queries.

database management system

A systematic approach to storing, updating, securing and retrieving information stored as data items, usually in the form of records in one or more files.

DBMS

DataBase Management System.

debug

To detect, trace and eliminate errors in computer programs.

default

A software function or operation which occurs automatically unless the user specifies something else.

delete key

Personal computers normally allow deletion of typing mistakes by either the backspace key or the Del key. Users must either specify which of these keys they wish to use, or set their communication software to match whichever key the network expects.

DHCP

Dynamic Host Configuration Protocol. Supports booting workstations and other devices that need information from outside before they can complete the booting process, such as an IP number or name of program file to download.

dial-up

To connect to a computer by calling it on the telephone.

dictionary file

A special form of machine-readable codebook that contains information about the structure of a datafile and the locations and, often, the names of variables variables in the datafile. Typically, you use a dictionary file and a datafile together with statistical software; the statistical software uses the dictionary so that you may specify variables by name, rather than having to specify their locations in the file.

digital

Used in computerese to describe information that can be represented by a collection of bits.

direct access

The ability to read or write data directly from or to any location on a storage device without having to refer to data that was previously written. Files written with direct access do not have to be read sequentially starting at the beginning.

directory

A logical container of files and other directories; synonymous with folder. Typically implemented as a file that contains pointers (directions) to files or other directories.

disk or diskette

A small, flat, either rigid or floppy magnetic disk for storing data permanently. Magnetic medium for data storage. Either "floppy" diskettes (720K to 1.4 megabytes), or "hard" disks (usually 20 megabytes or more).

display

A device that enables information, either textual or pictorial, to be seen but not permanently recorded. The most widely used kind is the cathode-ray tube.

distributed

Processing resides in more than one computer in a network.

distributed application

Application designed so that components run on different - but cooperating - systems on a network.

distributed database

The data resides in more than one physical database in a network. Access to the data involves more than one database server. Clients may have to connect to more than one server directly and integrate the data they receive according to the applications needs.

distributed file system

Allows files on remote nodes of a network to appear locally connected.

document

A medium and the data recorded on it for human use; for example, a report sheet or book. By extension, any record that has permanence and that can be read by human or machine.

documentation

A collection of organized documents or the information recorded in documents. Also instructional material specifying the inputs, operations and outputs of a computer program or system.

DOS

Disk Operating System. A Microsoft program that controls a computers transfer of data to and from a hard or floppy disk. DOS generally refers to the operating systems for the IBM PCs and their clones. Also the name of an old operating system on IBM mainframes.

dot-matrix printer

A printer that creates each character from an array of dots. The dots are formed by pins striking a ribbon against the paper, one pin for each dot position. The printer may be a serial printer (printing one character at a time) or a line printer.

down

A computer is down when it is not running. It may be shut down for maintenance, hardware failure, or failure of the operating system or user program.

download

The transfer of information from a remote computer system to the users system. Opposite of upload.

downtime

The time interval during which equipment is nonfunctional.

drag and drop

A protocol supported by OPEN LOOK and Macintosh System 7 that allows a user to specify the input file to an application by dragging the icon representing the file onto the applications icon and dropping it there. OPEN LOOK also recognizes dragging the icon into the applications input panel. For example, dragging a files icon into the printool application causes it to be printed.

drive

A generic term used to identify the equipment that serves as a player or recorder for a storage medium.

dump

A printed representation of the contents of a computer storage device, usually main memory, backed-up when a system crash or other failure has occurred. As a verb, refers to a large amount of data.

E

edit

To enter, modify or delete data.

editor

A program that permits the review and editing of the contents of a file.

e-mail

electronic mail. Information exchanged by electronic means in a manner analogous to that provided by the postal service.

e-mail address

The way you specify where an E-Mail message should be delivered.

e-mail server

A computer system that provides MTA, mailbox storage and directory services and optionally UA services.

e-mail service

UA, MTA, mailbox storage, and directory service.

encapsulation

Combining or defining a data structure of attributes and a group of associated functions and behaviors as a single object.

enter key

A special function key on a keyboard used to transmit a line or screen of data from a display screen to a computer. Often used interchangeably with return key.

environment

The setting in which computing takes place that is the aggregate of the hardware, software, policies and procedures relating to their use. The computing environment may be influenced by software, such as the operating system (for example, a UNIX environment) or the vendor (for example, an IBM environment).

erase

To remove data from a data medium, leaving the medium available for recording new data.

error message

A message that reports the detection of an error.

error checking

Uploading or downloading transfer check employed to identify errors in data transmission.

Ethernet

A local area network originally developed by Xerox for linking personal computers. Later adapted by DEC and Intel as well and subsequently adopted as an international standard called 802.3. It transmits data at 10 megabits per second. All computers on a network were originally connected to a coaxial cable up to one kilometer. Each computer monitors all transmissions, looking for packets containing its identifier as the destination. Only one signal may be present on the channel at a time and no single computer controls transmissions. Several upper layer protocols, such as DECnet and TCP/IP use Ethernet as an underlying transport mechanism. Ethernet is to be contrasted with other data link protocols such as token ring, DDCMP or SDLC. Uses CSMA/CD.

execute

To interpret a computer instruction and carry out the operations specified in the instruction.

F

fiber optics

A high speed channel for transmitting data. Made of high-purity glass sealed within an opaque tube. Much faster than conventional copper wire such as coaxial cable.

field

Usually the smallest data element in a record; a specified area used for a particular category of data; for example, columns used to represent a particular item of data, such as an employees wage (fixed field). The particular field is always used to record the same kind of information. In free field records, each field has an identifier that is present in the record and linked to the contents of the field.

file

A collection of any form of data that is stored beyond the time of execution of a single job. A file may contain program instructions or data, which may be numerical, textual or graphical information.

file format

The type of file, such as picture or text; represented as a suffix at the end of the filename (text = TXT or .txt, etc.).

file server

A computer designated to store software, courseware, administrative tools, and other data on a local- or wide-area network. It "serves" this information to other computers via the network when users enter their personal access codes.

folder

A place where a user's e-mail messages may be stored. Every user has a folder for new messages, and on most systems may create other folders for specific purposes.

font

A set of consistent size, shape or style of printer characters, including alphabetic and numeric characters and other signs and symbols.

foreground

High-priority processing, usually for realtime activities, automatically given precedence, by means of interrupts, over lower-priority processing.

form

The paper on which output data is printed.

form feed

The feature that automatically advances a roll of paper to the top of the next page or the next form when the printer has finished printing a document or form of one or more pages.

format

The defined structure of information that is recorded on magnetic media, displayed on a visual display device or printed on a page. Used as a verb, it means to put data into a predetermined structure or divide a storage medium, such as a disk into sectors, so that it is ready to receive data.

FORTRAN

FOrmula TRANslation. A high level scientific programming language.

fragment

Partial packet caused by a collision.

frame

A packet sent over a serial link.

freeware

Software that is distributed for free, with no license fee.

frequency

A measurement of the number of electromagnetic waves that pass over a given point in a given period of time.

FAQ

Frequently Asked Questions. A collection of information on the basics of any given subject. Often put together and archived on a server so that people don't waste bandwidth asking simple questions.

FTP

File Transfer Protocol. A program that allows for file transfers over the Internet.

FUD

Fear, Uncertainty and Doubt. "FUD factor"

function key

A keyboard key that gives an instruction to a computer, as opposed to keys that produce letters, numbers, marks of punctuation, etc.

G

garbage

Unwanted or meaningless information in memory, on disk or on a tape.

gateway

An electronic door between one computer network and another. A device or set of devices that connects two or more networks, enabling data transfer between them. When the networks are similar, a gateway routes packets or messages. When the networks differ, a gateway also performs extensive protocol conversion.

GIF

Graphic Interchange Format. Compuserves non-platform specific format for low-resolution, compressed graphics interchange.

gopher

A client program available via the Internet that allows users to review and retrieve information on other host systems via easy-to-use menus.

graphic

A computer-generated picture produced on a computer screen or paper, ranging from simple line or bar graphs to colorful and detailed images.

Groupware

Software that serves the group and makes the group as a whole more productive and efficient in group tasks. Example: Group Scheduling.

GUI

Graphical User Interface. Defines a format for scroll bars, buttons, menus, etc., and how they respond to the user.

H

handshaking

A procedure performed by modems, terminals, and computers to verify that communication has been correctly established.

hang

When a computer freezes, so that it does not respond to keyboard commands, it is said to "hang" or to have "hung."

hard copy

A printed copy of machine output in a visually readable form.

hard disk

A data-recording system using solid disks of magnetic material turning at high speeds.

hardware

Physical computer equipment such as electrical, electronic, magnetic and mechanical devices.

hardwired

Circuits that are permanently interconnected to perform a specific function, as distinct from circuits addressed by software in a program and, therefore, capable of performing a variety of functions, albeit more slowly. Also used to describe a non-switched connection between devices.

header

The portion of a message, preceding the actual data, containing source and destination address and error-checking fields.

help

Users in need of help can often issue a command such as "?" to access on-line help and tutorial systems.

hierarchical file

A hierarchical file is one that contains information collected on multiple units of analysis where each unit of analysis is subordinate to another unit. For example, if the physical housing structure is one unit, and individual persons within the structure is another unit, the person records are subordinate (e.g. related to) the housing unit. An example would be the Current Population Survey Annual Demographic File which has household, family, and person units of analysis. Studies that include data for different units of analysis often link those units to each other so that, for instance, one can analyze the persons as they group in a structure. Such studies are sometimes referred to as having a relational structure.

hierarchical file structure

A format for storing hierarchical files . Each unit of analysis has its own record structure or record type . Different units of analysis do not necessarily have the same number of bytes or characters as the records for other units of analysis. In order to give such a file a common physical record length , short logical records are typically "padded" with blanks so that they will all be the same physical record length. A hierarchical file can be also be stored in a rectangular file . For instance, the Survey of Income and Program Participation is distributed both ways; users can choose the format they prefer. Typically, the hierarchical file structure is more space-efficient but more difficult to use.

host

A computer that is made available for use by multiple people simultaneously.

host computer

In the context of networks, a computer that directly provides service to a user. In contrast to a network server, which provides services to a user through an intermediary host computer.

HTML

Hypertext Markup Language. A convention of codes used to access documents over the World-Wide Web. Without HTML codes, a document would be unreadable by a Web browser.

HTTP

HyperText Transfer Protocol. Extremely fast protocol used for network file transfers in the WWW environment.

hub

A device that is a center of network activity because it connects multiple networks together.

hyperlink

A pointer that when chosen displays the item to which it points. It typically takes the form of a button or highlighted text that points to related text, picture, video, or audio. Hyperlinks allow non-linear exploration of media that contain them.

hypermedia

Media (such as text, graphics, video, audio) that contains hyperlinks.

hypertext

A document which has been marked up to allow a user to select words or pictures within the document, click on them, and connect to further information. The basis of the World-Wide Web.

I

icons

On-screen pictu