Computer monitor1. Alternatively referred to as a video display terminal (VDT) and video display unit (VDU), a monitor encompasses a display screen for video images and casing that holds it. In its most common usage, monitor refers only to devices that contain no electronic equipment other than what is essentially needed to display and adjust the characteristics of an image.

Like most early TVs, the early computer monitor's were comprised of a CRT (Cathode Ray Tube) and a fluorescent screen. Today, all monitors are created using flat panel display technology, like that shown in the image.

Why is a monitor an output device?

A monitor is only used to display (output) information from a computer and provides no source of input. Because a typical monitor sends no information back to the computer it is an output device.

Note: Newer PCs have touchscreen monitors, which allow the user to touch their computer and interact with what is shown on the screen. If the monitor is a touchscreen because it is providing input back to the computer these types of monitors are considered Input/Output devices.

Related pages

2. Monitor is a term to describe the process of viewing or watching over someone or something.

3. Used frequently with machines utilizing punch card input, a resident monitor was system software that came before, but was very similar to an operating system.

Also see: Display, Output device, RGB monitor, Security terms, Video terms, CRT