Back-up A duplicate copy of a file,made in case of accidental loss or damage to the origianl. Back-ups can be made onto a second hard drive fitted to the computer, or on removeablemedia such as CD-Rs.

Benchmark Software Standard,most widely used program packages. For example your compter has Microsoft Office XP or/and Microsoft Works. One or the other comes pre installed on many PCs.

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

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

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

Bits per second(bps) A measurement for the speed with which data can be sent to or from a computer via a modem

Boot or boot up To switch on the computer 

Broadband High-speed Internet access via either an ADSL, Cable or Satellite connection.

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

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

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