Definition of CPU
The CPU (central processing unit) is the part of a computer controls the interpretation and execution of instructions. Generally, the CPU is a single microchip, but that doesn't necessarily have to be the case. In the consumer desktop and laptop market, the CPU market is dominated by Intel, AMD, and IBM. These manufacturers supply the computer makers such as Dell, HP, and Apple.
Due to its importance to every computing task, the speed of the CPU, usually measured in gigahertz (GHz) is the number that most vendors use in their marketing campaigns. In the past, the larger the number, the faster the computer could be expected to be. However, in recent years, the speed of the CPU has had less impact as other components of a computer take on more and more of the workload. Also, differences in technology mean that a slower chip that performs more calculations per cycle can actually be faster than a higher rate chip doing fewer calculations per cycle.