The computer is one of the most intelligent inventions of man. It is a machine which can carry out automatic calculation, store data and perform logical operations. The computer has a device which stores data. The earlier computers were very huge, expensive and performed only certain functions. However, today the computers are many times more capable, cost effective, light in weight and occupy less space. They also fit into mobile phones. The computers are very useful to people who are businessmen, bankers, students, government servants and houses wives. Though these computers are easy to use, they are totally dependent on electricity and internet facility. If these facilities are not available, it is not possible to use the computer. Virus is the biggest enemy of the computers. If the virus hits the computer, the computers cannot be operated. Everyone should know how to use a computer. It is a necessity and not a luxury anymore.