The CPU is the computer. That’s where all the magic happens. It performs all the math and that’s where all the logical operations happen. The CPU also controls the rest of the system and is responsible for handling the I/O (Input/Output) operations that and program may carry out.
This contrasts with external components such as main memory and I/O circuitry because those components aren’t actually performing computations. Also, CPUs differ from other number-crunching chips like GPUs (Graphics Processing Units) in that GPUs do not possess any ability to control other parts of the system.
The CPU Really is The Computer
It’s really that simple. When you are using a computer, you are using the CPU. Everything else, the storage controllers, RAM, USB ports, Monitor, Mice, Speakers, etc, is just to get data into and out of the CPU.