A duplicate copy of a file, make in case of accidental loss or damage to the original.

Benchmark software Standard, most widely used program packages. This book uses Microsoft Office 97 (Standard Edition) and Microsoft Works Suite 99 as its Benchmark software. One or other of the two packages comes preinstalled on many PCs.

Basic Input/Output System. Instructions that control the computer's hardware at the most basic level. The BIOS tells the operation system which hardware to expect to come into operation and how it is arranged.

The smallest unit of computer memory, Bit is a contraction of 'binary digit'. Its value can be only 0 or 1. All computers use the binary system to process data.

An on-screen image made up of tiny dots, or pixels. See Pixel.

A measurement for the speed with which data can be sent to or from a computer via a modem.

To switch on the computer.

An accidental error or fault in a computer program. Bugs may cause programs to crash, which can lead to data loss.

An on-screen image that can be clicked on using the mouse. Clicking on a button performs a function, such as opening a dialogue box or confirming an action.

A unit of computer memory, made up of eight bits. It takes one byte of memory to store a single character, such as letter of the alphabet.