CPU stands for Central Processing Unit, which is often referred to as the brain of a computer. Its primary function is to execute instructions from programs by performing basic arithmetic, logic, control, and input/output operations. The CPU processes data by retrieving instructions from the computer's memory, decoding them, and executing the required tasks. Modern CPUs come with multiple cores, allowing them to perform several operations simultaneously, improving overall system performance. CPUs are integral to all computing devices, including PCs, laptops, and smartphones, facilitating the execution of software applications and system functions.