Closed-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 (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.
CCTV Cameras are available in color, monochrome or cameras that have the ability to switch between color and monochrome (day/night CCTV cameras). The CCTV cameras that switch between color and monochrome are intended for environments of low lighting at various times. There are 2 reasons for using a CCTV camera that can switch between color and monochrome, monochrome CCTV cameras are much more sensitive to low lighting environments, and monochrome CCTV cameras can also be used with Infra red lighting. When there is adequate available light there is the added advantage of using a color CCTV camera for recording color information, for example the color of a car or a person's clothing.
The primary function of a CCTV camera is to convert light into a video signal; all CCTV cameras require an optical lens to focus the light onto an image sensor located directly behind the lens inside the CCTV camera. There are two types of image sensor available, a CCTV camera with a CMOS (Complementary Metal- Oxide Semiconductor) image sensor chip and the other more common type that uses a CCD (Charge Coupled Device) imaging sensor chip. The majority of CCTV cameras and Video Camcorders use a CCD imaging sensor, whereas CMOS imaging sensors are more commonly used in webcams, budget home security cameras and digital photography cameras. CCD cameras are capable of creating a much clearer and higher resolution image.