The property of the transistor, being able to switch between two different states (on-off) is very important for a computer's function. In a computer the transistor can be made to switch between two binary states called 0 and 1. The transistor is used by the computer to do calculations, etc. In today's complex computers there are several thousands, even millions of transistors. In a computer it is not present as a single isolated item, instead it is part of something that is called an integrated circuit.