CCTV, which stands for closed-circuit television in its full form, is a TV system where signals are transmitted and monitored primarily for video surveillance and security use cases. In the security industry, however, CCTV isn’t the only abbreviation worth knowing the meaning of— browse our list below to gain a better understanding of the most widely-used terms.

CCTV Acronym Definition
A/VAudio / video
AVIAudio Video Interleave - An audio-video standard designed by Microsoft.
AESAuto electronic shutter - the ability of the camera to compensate for moderate light changes by adjusting the camera shutter without the use of auto iris lenses.
AGCAutomatic gain control - this feature adjusts the brightness level of the video to keep it at a consistent level.
BLCBack light compensation - a feature on newer CCD cameras which electronically compensates for high background lighting to give detail which would normally be silhouetted.
BNCBayonet Nut Coupling - A commonly used connection for audio/video (A/V) applications. Uses a mount similar to the way a bayonet knife is mounted onto the end of a rifle, BNCs are used to connect a variety of different coaxial cable types. After the plug is inserted, it is turned, causing pins in the socket to be pinched into a locking groove on the plug.
CAT5Category 5 (cable) - the type of cable that is used in networking applications.
CCDCCTV security cameras produce images using CMOS or CCD (Charge Couple Device) chips. CCD chips are higher quality and produce a better image than CMOS.
CMOSComplementary metal oxide semiconductor - Pronounced see-moss, CMOS is a widely used type of semiconductor.
CCTVClosed-circuit television.
DVRDigital video recorder - a digital video recorder is basically a computer that converts the incoming (analog) signal from the cameras to digital, and compresses it, and stores it. The DVR replaces the function of a multiplexor (or quad or switcher) and a security VCR. There are many advantages of digital video recorders over their analog counterparts.
FPSFrames per second - in digital video applications, refers to the number of video images that can be captured, displayed, or recorded in a second. Also referred to as the 'frame rate' or 'refresh rate'.
GHZ Gigahertz
JPEGPronounced "jay-peg" and stands for "Joint Photographic Experts Group" who designed the standard. This is a standard way of compressing images which works particularily well for photographic images (as opposed to graphic art).
MPEG (or MPG)Pronounced "em-peg" and stands for "Motion Picture Experts Group" who designed the standard. This is a standard way of compressing audio and video files. (It's also the technology behind the now world-famous MP3 music files.)
NTSCNational Television Standards Committee - analog video standard used in North America and most of South America. See here for more info.
PALPhase Alternating Line - predominant analog video standard used in Europe and Asia. See here for more info.
POEPower Over Ethernet - an adaptor that allows you to transmit power to a security camera through CAT5 (aka ethernet) cable.
PTZPan-tilt-zoom - PTZ cameras allow you to adjust the position ('pan' is side-to-side, 'tilt' is up-and-down) and focus ('zoom') of the camera using a remote controller. Due to this added functionality, these cameras tend to cost much more than non-PTZ cameras
RG59An RG-59 is a common coax cable used in CCTV applications.
RCA An RCA connector, sometimes called a phono connector or cinch connector, is a type of electrical connector commonly used to carry audio and video signals. The name "RCA" derives from the Radio Corporation of America, which introduced the design by the early 1940s to allow mono phonograph players to be connected to amplifiers.
S/N RatioSignal to noise ratio; this number represents how much signal noise the camera can tolerate and still provide a good picture. The higher the number the better.
SECAMSequential Color with Memory - analog video standard used in France and other countries. See here for more info.
VCRVideocassette recorder; an electronic device for recording and playing back video images and sound on a videocassette.