What is a CPU and what does it do?

We get asked a lot of questions regarding computers and always answer them for free at Just Geek IT .  One of the most asked question is, “what is a cpu?  Well to be honest, it is the brain of the computer much like we have a brain.  The  CPU has four primary functions: fetch, decode, execute, and writeback.  We just opened more questions about the CPU I bet.

Fetch sounds exactly what it means.  The CPU retrieves information from the computer’s memory.

Decode – When the CPU retrieves the data it comes in bits.  The CPU decodes the bits and translates it to information.

Execute – When the CPU translates the data into information it then tells the computer to execute the information.  Opening a program is an executable command that comes from the CPU.

Write back – The CPU takes this output and writes it into the computer’s memory.


If you have any further computer questions, please feel to let us know.