A central processing unit (CPU) (also called a central processor, main processor, or just processor) is the most important processor in a given computer. Its electronic circuitry executes instructions of a computer program, such as arithmetic, logic, controlling, and input/output (I/O) operations. The central processing unit (CPU) of a computer is a piece of hardware that carries out the instructions of a computer program. It performs the basic arithmetical, logical, and input/output operations of a computer system. The Central Processing Unit (CPU) has the following characteristics: The CPU is regarded as the computer's brain. The CPU is responsible for all data processing operations. It saves information such as data, intermediate results, and instructions (program). It directs the operation of all computer components.