CCTVClosed-circuit television (CCTV) is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors.
It differs from broadcast television in that the signal is not openly transmitted, though it may employ point to point, point to multipoint, or mesh wireless links. CCTV is often used for surveillance in areas that may need monitoring such as banks, casinos, airports, military installations, and convenience stores. It is also an important tool of distance education.
In industrial plants, CCTV equipment may be used to observe parts of a process from a central control room, for example when the environment is not suitable for humans. CCTV systems may operate continuously or only as required to monitor a particular event. A more advanced form of CCTV, utilizing Digital Video Recorders (DVRs), provides recording for possibly many years, with a variety of quality and performance options and extra features (such as motion-detection and email alerts). More recently, decentralized IP-based CCTV cameras, some equipped with megapixel sensors, support recording directly to network-attached storage devices, or internal flash for completely stand-alone operation.
Surveillance of the public using CCTV is particularly common in the USA and UK, where there are reportedly more cameras per person than in any other country in the world. There and elsewhere, its increasing use has triggered a debate about security versus privacy
A digital video recorder (DVR) or personal video recorder (PVR) is a device that records video in a digital format to a disk drive, USB flash drive, SD memory card or other memory medium within a device. The term includes stand-alone set-top boxes, portable media players (PMP) and recorders (PMR as camcorders that record in memory cards) and software for personal computers which enables video capture and playback to and from disk. More and more manufacturers have started to offer television sets with digital video-recording hardware and software built into the television itself; LG was first to launch one