Generally, the monitor refers to the display. Some graphics cards can output dual displays, and the other is called the monitor. The development of monitors has experienced the development process from black and white to color, from flashing to non-flashing, from CRT to LCD and then to BSV liquid crystal technology.

The monitor is an important part of the closed-circuit monitoring system, is the display part of the monitoring system, is the terminal equipment of the monitoring system, acts as the "eye" of the monitoring personnel, and also plays a key role in the post investigation.