I/O devices, or Input/Output devices, are essential components of a computer system that allow it to communicate with the outside world. Input devices, such as keyboards and mouses, enable users to send data and commands to the computer. Output devices, like monitors and printers, display or produce results from the computer's processing. These devices work together to facilitate interaction between users and computers. For example, when a user types on a keyboard, the input is processed by the computer, and the results can be shown on a monitor. This seamless exchange of information is crucial for effective computing.