An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system (such as a computer) to the outside world.
In computing, input/output, or I/O, refers to the communication between an information processing system (such as a computer), and the outside world. Inputs are the signals or data sent to the system, and outputs are the signals or data sent by the system to the outside.
Examples of output devices:
Some later game systems like the Nintendo Wii offer feedback via vibration and possibly a speaker on their controllers, thus making the controller a I/O device, rather than an input device.