The primary purpose of a CPU (Central Processing Unit) in a computer system is to execute instructions and manage tasks. It is often referred to as the brain of the computer, where all processing occurs. The CPU carries out operations specified by the software, including arithmetic, logic, and control tasks. Its speed and efficiency directly influence overall system performance, enabling applications to run effectively and providing a responsive user experience. By processing billions of instructions per second, the CPU is crucial in ensuring that the system operates smoothly and competently meets users' demands.