A legitimate question about the very common term peripheral device, which is often used in the majority, peripheral devices!
With a computer, no matter whether MAC OS, Linux or Windows, peripheral devices can be seen as so-called auxiliary devices and external extensions to the computer. A peripheral device is a piece of hardware that can function as an input device or output device that gives a computer additional functionality.
However, peripheral devices are not necessary for the computer to perform its basic tasks and functions. They can be seen as an improvement and enhancements that the user needs.
Unlike a computer, a peripheral device is usually unable to work on its own and the computer must function properly. The peripheral devices take on different tasks and roles, or functions.
To name a few peripheral devices:
sound card, loudspeaker , projector, mouse, monitor, touch screen, projector, printer, plotter, scanner, digital camera, joystick, keyboard, microphone, etc.