An output device is any device used to send data from a computer to another device or user. Most computer data output that is meant for humans is in the form of audio or video. Thus, most output devices used by humans are in these categories. Examples include monitors, projectors, speakers and printers.

A computer monitor is an output device that displays information in pictorial form. The display device in modern monitors is typically a thin film transistor liquid crystal display (TFT-LCD) with LED backlighting having replaced cold-cathode fluorescent lamp (CCFL) backlighting. Older monitors used a cathode ray tube (CRT). Monitors are connected to the computer via VGA, Digital Visual Interface (DVI), HDMI, DisplayPort, Thunderbolt, low-voltage differential signaling (LVDS) or other proprietary connectors and signals.

Originally, monitors were used for data processing.From the 1980s onwards, computers have been used for both data processing and entertainment,

Modern monitors are easily interchangeable with conventional television sets. However, as monitors do not necessarily include integrated speakers, it may not be possible to use a computer monitor without external components.