What is a computer?

A computer is an electronic device, operating under the control of instructions stored in its own memory. These instructions tell the machine what to do. The computer is capable of accepting data (input), processing data arithmetically and logically, producing output from the processing, and storing the results for future use. Most computers that sit on a desktop are called "PCs," or personal computers

Computers can be generally classified by size and power, although there can be considerable overlap. Following are descriptions of several different types of computers.