what is computer A computer is a machine that can be programmed to automatically carry out sequences of arithmetic or logical operations ( computation ). Modern digital electronic computers can perform generic sets of operations known as programs . These programs enable computers to perform a wide range of tasks. The term computer system may refer to a nominally complete computer that includes the hardware , operating system , software , and peripheral equipment needed and used for full operation; or to a group of computers that are linked and function together, such as a computer network