A peripheral is a piece of equipment that is attached to a host
computer without being a part of it and is instead dependent on
the host. It broadens the capabilities of the host, but does not
form part of the core computer architecture. Common examples of
peripherals include computer printers, scanners, headphones,
speakers, and webcams. Some peripheral devices can be attached
directly to the computer via a cord, cable, or USB device.
Others can be attached wirelessly. It is not always clear
whether or not something is a peripheral. A video capture card
inside a computer case is not part of the center computer, but
it is however, contained in the case. Ultimately though, it is
not a significant issue.