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Peripheral or peripheral devices, also known as Input-Output devices, enable the computer to remain in contact with the external environment or expand the computer's functionality. Peripheral devices enhance the computer's capability by making it possible to enter information into a computer for storage or processing and to deliver the processed data to a user, another computer, or a device controlled by the computer. Internal peripherals are connected directly to the address, data, and control buses of the computer. External peripherals can be connected to the computer via USB or a similar connection.