Here is some introductory material on video signals. Check those if you are looking for basic information on video signals.
There are many different video formats in use in video systems. They are used in different applications for various technical and economical reasons. Here is a short primer of the most commonly used signal formats from the best to worst in picture quality:
Composite video is a single video signal that includes all sync, blac&white and color information all in same signal. Composite video signal is the most often used video signal format in TV broadcasting industry and it is used anywhere from TV camesras to TV broadcasts upto consumer video equipment interconnections. Composite video signal is most often transported using one 75 ohm coaxial cable terminated with RCA or BNC connectors so that center pin carries the signal and the outer shield of the connector is signal ground. Composite video signals have a number of unavoidable image problems because of inherent limitations of the color TV systems (PAL, NTSC and SECAM systems). The main problem is, once the colour (C) and the black and white (Y) information have been put together, they can no longer be perfectly separated due to fundamental design limitations of the color TV systems. In PAL composite video signal is modulated to 4.43 MHz subcarrier (actual frequency is 4.43361875 MHz + 5 Hz). In NTSC video system the color information is modulated to 3.58 MHz subcarrier (actual frequency is 3.579545 MHz + 10 Hz).
S-Video is one of the high quality methods of transmitting a television signal from a device such as a Camcorder, DVD, or a digital satellite receiver. S-video interface separates the color information (Chrominance) from the brightness (Luminance), which prevents nasty things like color bleeding and dot crawl, and helps increase clarity and sharpness. S-Video is "essentially" the same as Chroma & Luma, Brightness & Color, or y/c. They all mean the same thing, in a vague sort of way. Don't get confused here if you see different names for this connection.
There are many omponent video formats in use in use. The most commonly used component vidoe formats are RGB, YPbPr and YCbC. The RGB format is the basic format in which the signal is generated in the vidoe camera. In other formats the Y component of this signal is the black and white information contained within the original RGB signal. The Pb and Pr signals are colour difference signals, which are mathematically derived from the original RGB signal. It is important to realize that what is commonly called "component video" (YPbP or YCbC) output and RGB video output are not the same and are not directly compatible with each other, however, they are easily converted either way, at least in theory.
PDC is an invention that enables you to set your video recorder to tape a programme, knowing that it will be recorded in full, even if the programme is shown later than advertised.
Teletext is a method to transfer text pages to television sets withing the TV broadcasts. Teletext system is in use in many European countries.
FCC adopted system in USA to to block the display of television programming based upon its rating. The V-Chip reads information encoded in the rated program and blocks programs from the set based upon the rating selected by the parent.
Time code is a time information included in the video signal or stored separately to a taped video signal. This time information is very useful in video editing and post-processing applications.