Component video is a video signal that is transmitted as several separate channels (as opposed to a composite video signal, such as NTSC or PAL, which is transmitted as a single signal).
Most component video signals are a variation of the red, green and blue signals that make up a television image. The simplest type, RGB, consists of the three discrete R, G & B signals sent down three cables. Another type consists of R-Y, B-Y and Y, delivered the same way. Y is the luminance channel, R-Y is the red component minus the luminance information, and B-Y is the blue component minus the luminance information. See YUV and YIQ for more information on this color space.
Component digital video signals are sometimes referred to as 4:2:2, meaning that in an 8-bit environment, 4 bits are dedicated to the Y component while 2 bits each are dedicated to the B & R components. The luminance or Y channel carries most of the image detail and is, therefore, assigned more bits.
S-Video is also considered a component signal, in which the luminance and chrominance (color) channels are transmitted separately.
Examples of international composite video standards are: