The word computer comes from the word “compute” which means “to calculate”. Hence people usually consider a computer to be a calculating device that can perform arithmetic operations at high speed.

A computer is often referred to as a data processor because it can store, process and retrieve data whenever required.

Computer is defined as a device that operates upon data because more than 80% of work done by today’s computer is data processing.

Data processing consist of three sub activities:

  • Capturing input data
  • Manipulating the data
  • Managing output result


Main characteristics of computer are as follow:

  1. Automatic.  An automatic machine works by itself without human intervention. computers are automatic machines because once started on a job, they carry out the job (normally without any human assistance) until it is finished. However,computer being machines cannot start themselves and cannot go out and find their own problems solutions. We need to instruct using coded language that specify exactly how it will do a particular job.                                            
  2. Speed. A computer is a very fast device. It can perform in a few seconds,the amount of work that a human being can do in an entire year- if he/she worked day and night and did nothing else. In other words , a computer can do in  a few minutes what would take a man his entire life.