YCbCr is a family of color spaces traditionally used in analogue television.

It's an early attempt at a perceptually uniform color space, but prioritizes backwards combatability with black and white television signal.

It's described by a luma component (Y) and two chrominance components, called U (blue projection) and V (red projection) respectively.

Compared with RGB it typically has reduced bandwidth and improved masking of compression or transmission artifacts. There are other color encodings with similar properties, but YUV was popularly used in television and some photography and as such remains in use for compatibility reasons.

Y - Luma
U - Blue (or yellow)
V - Red (or green)