The central processing unit (CPU) is the main component of a computer that performs most of the processing tasks. It is sometimes referred to as the "brain" of the computer because it executes instructions from the computer's software and performs mathematical and logical operations. The CPU is responsible for fetching, decoding, and executing instructions, and it is also responsible for communicating with other parts of the computer, such as memory and input/output devices. The CPU is a complex microprocessor that contains millions of transistors and is designed to execute instructions quickly and accurately.