CPU is also known as Central Processing Unit, and it’s what is inside a computer that does all the processing of data. Input refers to information being accepted by a computer from input devices such as a keyboard, mouse, or touch screen. Output refers to displaying information onto output devices such as monitors, printers, or speakers which in turn create sound waves. Ultimately these two terms refer to different parts of computing at different levels – where input/output doesn’t need a life outside of itself and CPU needs the rest in order for it to work. This is because CPUs require both data in and out.