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.

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).

Retention, storage and preservation

Most CCTV systems record and store digital video and images to a Digital Video Recorder or in the case of IP cameras directly to a server, either on-site or offsite.

The amount of data stored and the retention period of the video or pictures are subject to compression ratios, images stored per second, image size and duration of image retention before being overwritten.

Recordings are usually kept for a pre-set amount of time and then automatically archived, overwritten or deleted. The amount of time the videos are kept allow retrieval and review in the event a crime was committed or the information needs to be studied for any number of reasons.


These days security alarms are capable of performing a variety of functions, many of which surpass the traditional role of the alarm system in the home. One such function is known in the home security industry as home automation. Alarm systems that are designed for home automation are generally constructed so that they can perform many different roles in addition to their traditional use as a security device. Many alarm companies create home automation packages by bundling popular security alarms with other types of equipment that allows the alarm to perform new functions.

While home automation alarm systems tend to vary in terms of what they are capable of doing a vast majority of home automation systems on the market can typically perform the same basic set of functions. One of the main functions of a home automation alarm system, aside from acting as a security alarm for the home, is the control of certain devices within the home. The most common devices that home automation security alarms can control are the lights within the home. Lighting controls also allow the homeowner to save money on their electricity bill, not to mention the fact that home automation alarms with lighting controls also allow the homeowner to take a much more active role in their home security by determining which lights need to be left on and when.