The function of the CPU (Central Processing Unit) in a computer system is to execute instructions and manage the flow of data within the system. Often referred to as the "brain" of the computer, the CPU performs arithmetic, logic, and control operations necessary for running programs and processing tasks. It communicates with other hardware components, such as memory and input/output devices, ensuring efficient operation. The performance of a CPU is often defined by its clock speed, number of cores, and architecture, which collectively influence overall computing power.