The purpose of a computer's CPU (Central Processing Unit) is to perform the basic computations and control operations of a computer. Often referred to as the "brains" of the computer, the CPU executes instructions from software applications by performing arithmetic calculations, logic operations, and data processing tasks. It interprets and carries out commands, interacting with the computer's memory and input/output devices to ensure overall system functionality. The CPU's speed and efficiency significantly impact a computer's performance.