CCTV is the abbreviation of Closed Circuit Television. It refers to a closed-circuit television surveillance system, a professional security and management system centered on closed-loop transmission. Its core feature is that video signals are transmitted only within a designated private or local network without public broadcasting. It is mainly used for real-time monitoring, signal storage, image display and anomaly warning in specific areas. As one of the most basic and commonly used core devices in modern security systems, it is widely applied in various public areas, enterprises and private premises.

A complete CCTV system consists of four core modules: front-end collection, signal transmission, back-end control and storage, and terminal display. The front end captures images and converts them into signals, which are transmitted to the back end through transmission media. The back end distributes signals to display terminals and stores data. Operators can control devices, play back recordings, and the system will automatically trigger alarm linkage in case of abnormalities.

In practical applications, the core functions of a CCTV system include real-time monitoring, video storage, intelligent analysis, alarm linkage and permission management. It is widely used in residential communities, stores, factories, banks, roads, schools, hospitals and other scenarios. It can not only prevent security risks and protect public and private property safety, but also assist daily management and improve work efficiency.