Not so much a physical connector as a standard for transmitting video over various connectors, the RGB format is occasionally used in TV connections, but is more commonly found as a connection for computer monitors. The reduced interference from splitting the red, green, and blue signals and transmitting them separately provides a high quality analog signal.
RGB is a type of component video signal consisting of three signals — red, green, and blue — carried on three separate cables. Extra cables are sometimes needed to carry synchronizing signals. This type of video signal is widely used in Europe via the standard SCART connector. Outside Europe, S-Video is largely used in place of RGB. However, almost all computer monitors around the world use RGB (though this will eventually be phased out in favour of DVI).
Physical RGB connectors come in several forms:
Named after its 'Bayonet' locking mechanism and its two inventors 'Neill' and 'Concelman'. This connector is generally only found in professional equipment, in place of the RCA connector. It has superior signal transfer, and its bayonet mechanism means that it locks in place.
"RCA" derives from the Radio Corporation of America, which introduced the design by the early 1940s to allow phonograph players to be connected to radios. It is a low cost and low quality analog connector, commonly used in audio equipment. The image to the left shows the Red, Green, and Blue RCA Connectors.
(Red, Green, Blue, Horizontal, Vertical) A five-wire signal where the red, green, and blue video signals, as well as the horizontal and vertical synchronisation signals are split into their own cables. Found primarily on professional video equipment.
Common in Europe, this multi-purpose connector can carry various kinds of analog audio and video signal, including RGB. Its great advantage is that a single connector can carry multiple kinds of signal (though not necessarily at the same time).
Also known as a DE-15 connector, this is the video connection used on almost all computer monitors and provides a high quality connection that screws in place. It is found on newer TV's as a convenient way to connect to a computer.
For more information about other connectors see here.