YUV is the color encoding system and analogue television (NTSC, PAL and SECAM) uses YUV. YUV is used for color image or video processing.
The Y in YUV stands for ‘Luma and luminance’ (the brightness) and U (blue-luminance) and V (red-luminance) for ‘chrominance’ (color).
Y ranges from 0 to 1 (or 0 to 255 in digital formats), U and V range from -0.5 to 0.5 (or -128 to 127 in digital formats).
See also RGB