A computer is a device, which under the control of a stored program, can accept data in a prescribed form, process the data ND supply the results as information. There are three points to note about this definition. Computer is a device: it consists of electronic parts working together to process data. A computer perform three marjor function which are, it accept data(input),it processes data,it suppliy data or information (output). We also have two major software which are system software AND application software.