Closed-circuit
television (CCTV), also known as video surveillance, 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
(P2P), point to multipoint, or mesh wireless links. Though almost all
video cameras fit this definition, the term is most often applied to
those used for surveillance in areas that may need monitoring such as
banks, casinos, airports, military installations, and convenience
stores. Videotelephony is seldom called "CCTV" but the use of video in
distance education, where it is an important tool, is often so called.
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 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 many
areas around the world. In recent years, the use of body worn video
cameras has been introduced as a new form of surveillance.
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