Closed Circuit Television (CCTV) is a video surveillance technology designed to monitor a variety of environments and activities. It is called closed circuit because, unlike broadcasting, all its components are linked. Moreover, unlike conventional television, this is a system designed for a limited number of viewers.

The circuit can be composed, simply, of one or more surveillance cameras connected to one or more video monitors or televisions, which reproduce the images captured by the cameras. Although, to improve the system, other components such as video or computers are often connected directly or linked by network.

They are fixed in a certain place. In a modern system, the cameras used may be remotely controlled from a control room, where their pan, focus, tilt and zoom can be configured. This type of camera is called PTZ (pan-tilt-zoom).