Input/output or I/O is the communication between an information processing system, such as a computer, and the outside world, possibly a human or another information processing system. Inputs are the signals or data received by the system and outputs are the signals or data sent from it. The term can also be used as part of an action; to "perform I/O" is to perform an input or output operation.
Besides providing abstractions like processes, address spaces, and files, and OS also controls all of the computer’s I/O devices.
For that, the OS should:
• issue commands to handle the I/O devices
• catch the interrupts
• handle the errors
• Provide the interface between devices and the rest of the system.
