Any machine that feeds data into a computer. For example, a keyboard is an input device, whereas a display monitor is an outputdevice. Input devices other than the keyboard are sometimes called alternateinput devices. Mice, trackballs, and light pensare all alternate input devices.
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) which converts the electronically generated information into human-readable form.