A computer is an information processing machine.

Computers process data to produce information.

The sets of instructions that humans give computers are called programs or software.

Software that carries out a particular type of task for a user is often called applications software.

There are many reasons for using computers:

• Computers can work much faster than humans;
• Computers never get tired or need a rest;
• Computers can do jobs that it would be dangerous for a human to do;
• Computers can store large amounts of information in a very small space;
• Computers can find information very quickly;
• Computers never lose or misplace information.

The three stages of computing are input, processing and output.

A computer works through these stages by ‘running’ a program. A program is a set of step-by-step instructions which tells the computer exactly what to do with input in order to produce the required output.