It is also known as a brain of the computer. It carries out instructions and computer programs and performs all the basic arithmetical and logical operations. CPU is installed in the motherboard on a specific area known as CPU socket.
The term CPU was first used in Computer industry in the early 1960's. Initially the term CPU was used to define a device for software execution and it came with the advent of the stored program computer.
Traditionally the term CPU refers to a processor which includes control unit and arithmetical logical unit.