CPU stands for Central Processing Unit. It is the primary component of a computer system that carries out instructions of a computer program. The CPU is often referred to as the "brain" of the computer, as it performs the majority of the calculations and operations that are necessary for the computer to function.
The CPU is responsible for fetching instructions from the computer's memory, decoding those instructions, executing them, and then storing the results back in memory. It is made up of several sub-components, including the arithmetic logic unit (ALU) which performs mathematical operations, and the control unit (CU) which manages the flow of data and instructions within the CPU and to other parts of the computer system.