The CPU stands for Central Processing Unit. It does all the processing for the entire system. Without it, your computer can’t do anything. It’s just dead without it.
The CPU or the Central Processing Unit is also called  the brains of the computer. No computer can ever operate without the CPU. Every action and key that you press on the computer, every command that you give it should go through the CPU in order for it to be implemented. Just as how important the brain is to the body so is the case with the CPU to the computer. The CPUs are usually classified based on the number of cores or processors that they have. For instance, they have a single core, dual core and quad core processors.
It is therefore very important.
