A method of combining an NTSC video signal's luminance and chroma into one signal for transmission over a coax cable, or RF. Used in television. Doesn't have very good color resolution, because it is difficult to re-seperate the luminance and chroma information as they were before they were originally combined. The device that does this, called a comb filter, has gotten more advanced but is still imperfect. S-video and RGB video are much clearer than composite for this reason.