Glossary of Computer Terms
These pages contains definitions of a number of
To search for the term that you require please click the letter that
the term starts with in the alphabetical links above.
As the subject of computers is a rather large one, even this list only
covers a small portion of the number of terms that are used in the industry.
If the term that you want defined is not included or you think that
you have a better definition of one of the terms that is defined,
us an email so that we can update this list.
- Ethernet networking (10 megabit/second) using 50 ohm coaxial cable attached
to T junctions on each computer and terminated at each end
- Ethernet networking (10 megabit/second) using 4 wire twisted pairs to
connect the computers to a hub
- Ethernet networking similar to 10baseT but capable of 100 megabit/second
- Access time
- The amount of time for data requested from memory or disk to become
available after the request was issued.
- Advanced Configuration and Power Interface, allows components of the system
to be powered down when they are not in use.
- Active Window
- the window that appears in front of any other windows on the screen. Any
keyboard entry into the computer will be processed first by this window.
- asynchronous digital subscriber line, a broadband connection to the internet
that works independently of your telephone but using the same line to give you
a high speed permanent connection. Asynchronous
means that the download speed is faster than the upload speed so its still
not suitable for hosting your own site.
- accelerated graphics port, a new type of slot specifically designed for
high speed graphics card
- The programs that you run on the computer to perform the tasks that you
- American Standard Code for Information Interchange, the method of encoding
characters used by most smaller computers.
- Active server pages, a web page scripting language produced by Microsoft.
- the most common bus used to provide access to hard drives, also called IDE,
more recent versions are ATA-2 (also called EIDE) and ATA-3
- Backing Up
- the process of copying your files onto removable media. This gives you a
copy of the files that you can recover from if something happens to the
- the process throughput of the given device usually measured in bits or bytes
- A screen resolution of 800 x 600
- basic input output system, a ROM chip that contains the instructions on how
to start up the computer and access the main bus systems.
- abbreviation of binary digit, the smallest unit of computer memory, can only
hold one or zero
- The process of loading and running that part of the operating system that
loads the operating system
- an unintentional error in a program that causes the program to not perform correctly in
- the communication channels within the computer, eg the address bus allows
access to the computers memory, the data bus transfers data, other buses provide
common formats for attaching devices
- button (screen)
- a graphical representation of a button on the screen which can be pressed by
selecting it from the keyboard or clicking on it using a mouse
- eight bits, can hold 256 different values, in single byte character sets
each value is assigned a different character
- An area of memory used to hold information being passed to and from slower
memory in order to speed up access
- compact laser disk - recordable, a media which can be written to once by CD-R
capable drives as well as being able to be read by many CD ROM drives
- CD ROM
- compact laser disk read only memory, holds up to about 650Mb of data and
programs which can be read into the computer but not updated
- compact laser disk - rewritable, a media which can be rewritten to as required
by CD-RW capable drives
- common graphics array, a display mode of 320 x 200 dots
- common gateway interface, a means of passing data between a web server and
an external application
- check box
- The little square boxes that appear to the left of some fields. They are used
as on-off switches. Where an X appears in the box the associated condition
applies, when the box is empty the associated condition does not apply. In text
mode check boxes are usually shown as [ ].
- chips found on the motherboard that handle memory management as well as the interfaces
to the peripherals.
- to press and immediately release a mouse button
- the place where data that you have cut or copied is stored until you are ready
to paste it.
- close button
- the small button with an X in it which appears at the right hand end of the
title bar in recent versions of Windows and OS/2.
- the smallest section of disk space that can be accessed by programs, depending
on the filing system used this will consist of one or more sectors.
- coder - decoder chip, compresses video data down to a smaller size without
a significant reduction in quality
- to join two strings together one after the other
- control menu
- the menu which appears if you select the system button at the left hand end
of the title bar.
- a small piece of information stored on your system for later use by the web site
that wrote it so that it can customize the supplied information to your requirements.
- core voltage
- the CPU runs on a lower voltage than the rest of the computer.
- central processing unit, the brain of the computer, comes in several varieties
which are identifiable by number (eg. 486) or name (eg. Pentium)
- someone who tries to break into other peoples computer, often with
- a moveable marker on the video screen which indicates the place on the screen
where the next action will occur
- cyan yellow magenta black, the colours used by most colour printers, by mixing
these four colours most other colours can be produced
- a data storage repository containing data organized in such a way as to
simplify its retrieval.
- double data rate memory using synchronous dynamic ram.
- default directory
- the current directory being accessed on each drive. The default directory on the
default drive is known as the current working directory.
- default drive
- the drive which will be used by file accesses where a drive letter is not
specified. Text based operating systems usually indicate the default drive as part
of the command prompt.
- as you add and delete files on your hard drive the individual files end up being
stored in a large number of fragments wherever there is free space on the drive. This slows
down the process of reading the file. To resolve this we need to defragment the drive.
- the background which appears behind the windows displayed on your screen.
- a piece of computer hardware that performs a specific function.
- dynamic host configuration protocol, a method of dynamically allocating IP
addresses to the devices on a network.
- digital resolution
- an enhanced resolution of a scanning device obtained by interpolation.
- also called folder, a table of contents for a related set of files.
- Microsoft's multimedia and gaming extensions.
- disk (floppy)
- now a 3-1/2" flexible magnetic platter onto which data can be stored,
contained within a rigid plastic case, earlier floppy disks were 5-1/4" or 8"
and contained within a cardboard cover.
- disk (hard)
- a number of rigid magnetic platters contained inside the computer, has a much
larger memory capacity than floppies
- Dynamic Link Library, common routines shared between programs that are placed
in a separate module external to the programs that are to use them.
- the process of transferring data from a server to your computer
- Denial of Service, bombarding a server with bogus requests so as to
so overload it that it is unable to process legitimate requests.
- disk operating system, provides the interface between your application
programs and the computer hardware, makes it possible to run the same programs
on different hardware configurations, still the most popular operating system in
- dot pitch
- the distance in millimetres between the holes in the shadow mask inside
of your monitor (or between the wires if your monitor uses an aperture
grill). All other things being equal the smaller the dot pitch, the sharper
- double click
- to click a mouse button twice in quick succession
- dots per inch, a measure of the sharpness of a printed image, the dots
placed by inkjet printers spread slightly so 20% higher dots are required to
obtain the same sharpness as a laser printer eg. a 600 dpi laser has the same
resolution as a 720 dpi inkjet.
- to move the mouse pointer across the screen while holding a mouse button
- a small utility program that acts as the interface between the operating system
and a specific hardware device
- extended graphics array, a display mode of 480 x 320 dots
- extended industry standard architecture, a 32 bit version of an ISA slot,
usually brown, also the bus associated with such slots.
- the most commonly used part of the internet, used to send text and image enhanced
messages to other internet users.
- Exabyte (Eb)
- 1024 Petabytes or 1 152 921 504 606 846 976 bytes (2** 60 bytes)
- a collection of related information eg. a document or program.
- a hardware or software barrier placed between your computer/network
and the internet to help protect your system from external attacks.
- the particular typeface used to display your text eg. Courier, Times New
- Foreground Application
- in multi-tasking operating systems (eg. Windows NT, OS/2) the application to
which the active window belongs. In task swapping operating systems (eg. Windows)
the application that is actually running.
- the command that you use to clean out the contents of a disk so that you
can reuse it.
- front side bus, the connection between the processor and the main memory.
- File Transfer Protocol, a method of transferring files across the Internet
- a part of a program which performs a particular task.
- Gigabyte (Gb)
- 1024 Megabytes or 1073741824 bytes (2** 30 bytes)
- a method of document retrieval via the internet, now almost completely superseded
- graphics processor unit. The central processing component of your graphics card.
- graphical user interface, a method of displaying information on the computer
screen in graphical form.
- someone who can write clever and fast code although not necessarily well
structured. This term is also incorrectly used to refer to people who try to break
into other people's computer systems.
- the physical components that make up a computer system
- pressing the F1 key usually brings up a help screen which provides further
information associated with the field or window that is currently active.
- Hyper Text Markup Language, the markup language used to define pages on the
internet that are downloadable via HTTP.
- Hyper Text Transfer Protocol, the method used to transfer documents to your
computer from the World Wide Web.
- a small image on the computer screen used to represent a file or part of the
- Integrated Drive Electronics, see ATA.
- a vast connection of computers using TCP/IP to communicate with each other.
Used to run applications such as FTP, Telnet, SMTP, POP3, Gopher, HTTP (WWW),
and many others that allow information to be shared around the world.
- one of a small number of fixed addresses on your computer that can
send signals to the CPU to interrupt the current processing with some
time critical processing relating to the attached device
- input/output, the act of reading or writing.
- industry standard architecture, the original standard for slots for provision
of add-on cards originally 8 bit then extended to 16 bit, usually black, also the
bus associated with such slots.
- the typewriter like input device attached to the computer.
- kilobyte (k)
- 1024 bytes (2 ** 10 bytes)
- Local Area Network, the hardware and software allowing sharing of resources
between computers located relatively close together