Computer is a modern electronic machine that is used for doing various jobs. The person operating the computer gives instructions and thus the computer works. A computer stores information in its memory and uses whenever it is needed. The person gives instructions to the computer in a language that a computer understands. The main parts of a PC are a centre processor with its disk drives, keyboards monitor, printer and a scanner. They have become importart part of our lives. It is used in measuring daily routine work, trade and commerce, diagnosing diseases, entertainment, games and sports, transport, educátional sector, researching space and what not. It has done great wonders in inventing e-mail, internet and robot. Nowadays computer helps to diagnose a disease. Computer is of great use to us also in the field of agriculture and business. It has lessened our work loads and made our life easy and comfortable.