Computer is a device that help man to work. Modern computers have the ability to follow generalized sets of operations, called programs . These programs enable computers to perform an extremely wide range of tasks. A "complete" computer including the hardware , the operating system (main software ), and peripheral equipment required and used for "full" operation can be referred to as a computer system. This term may as well be used for a group of computers that are connected and work together, in particular a computer network or computer cluster . Computers are used as control systems for a wide variety of industrial and consumer devices . This includes simple special purpose devices like microwave ovens and remote controls , factory devices such as industrial robots and computer-aided design , and also general purpose devices li...