Computer is an ultra modern electronic device for storing and analysing information fed into it . It has no capacity to do anything by itself . It works on the basis of commands given by the operator . The invention of computer has a long history . Computer was not invented overnight . It look long time and hard labour to invent computer . A computer consists of five major components . They are the input unit the output unit the memory unit the control unit and the arithmatic . 
A computer performs three function firstly it receives data secondly it processes data by various computations and thirds is that it emits data .