A peripheral is a piece of computer hardware that is added to a host computer in order to expand its abilities. More specifically, the term is used to describe those devices that are optional in nature as opposed to hardware that is either demanded or always required in principle. The term also tends to be applied to devices that are hooked up externally, typically through some form of computer bus like USB. Typical examples include joysticks, mouse, keyboards, printer scanners & printer consumables such as toner, ink, drums kits fuser units backup tapes.
