Computer may be discussed in two parts. The first part is hardware-the physical, electronic and electromechanical device that are thought as computers.The second part is software- the programs that control and coordinate the activities of the computer hardware and that direct the processing data.

The central piece is called either the computer, the processor, or usually the central processing unit.The term "computer" usually refers to those parts of the hardware in which calculation and other data manipulations are performed, and the internal memory in which data and instructions are stored during the actual execution of programs. The various peripheral, these are input and output, secondary memory devices are attached to CPU.

The Computer software include two parts, these are system software and application software, the former is often referred to as "systems".And the later may be provided along with the hardware by system supplier.

These complete hard ware/software products are called turnkey systems.