A Central Processing Unit, or CPU, is the primary component of a computer that performs most of the processing inside the system. It interprets and executes instructions from programs, making it essential for running software applications. The CPU consists of several parts, including the arithmetic logic unit (ALU), which performs calculations, and the control unit, which directs the operation of the processor. CPUs are often referred to as the "brain" of the computer because they handle all the data processing tasks. They come in various types and speeds, measured in gigahertz (GHz), which indicates how many cycles per second the CPU can perform.