Also known as a microprocessor, a CPU is the brains of a computer. To be more specific, a CPU fetches program instructions from RAM (input), interprets and processes it (execution) and then sends back the computed results so that the relevant components can carry out the instructions. - See more at: http://www.buildcomputers.net/what-is-a-cpu.html#sthash.bhHfH0k4.dpuf