1. A peripheral is a device attached to a host computer, but not part of it, and is more or less dependent on the host. It expands the host's capabilities, but does not form part of the core computer architecture.
2. Examples are computer printers, image scanners, tape drives, microphones, loudspeakers, webcams, and digital cameras.
3. Any device connected internally or externally to a computer and used in the transfer of data. A personal computer or workstation processes information and, strictly speaking, that is all the computer does.
4. Data (unprocessed information) must get into the computer, and the processed information must get out.
5. Entering and displaying information is carried out on a wide variety of accessory devices called peripherals, also known as input/output (I/O) devices. Some peripherals, such as keyboards, are only input devices; other peripherals, such as printers, are only output devices; and some are both.
Common peripherals :
1) Input device
1) Output device
2) Display device
3) Graphical output device
4) Computer display
A device such as keyboards, printers, or even your computer monitors are known as Peripheral Devices. Peripheral devices connect to the system unit through the ports on the computer.