Definition - What does Peripheral Equipment mean?
Peripheral equipment refers to non-essential devices or equipment connected to a host computer, usually externally, in order to extend its capabilities. Peripheral equipment may not be essential to the computer's operation, but it's often needed in order for a user to interact with the computer.
Techopedia explains Peripheral Equipment
The best examples of peripheral devices are input and output devices. Input devices are those that take external stimuli and send it to the computer for processing, such as keyboards, mice and microphones. Output devices take processed information and send it outside of the computer for human communication or inter-computer communication. This includes monitors, network adapters and printers. Internal peripheral devices, often called integrated peripherals, might include a CD-ROM drive or modem.