Chroma subsampling is a video compression technique that reduces the amount of color information stored in a video signal relative to its brightness information. The human visual system is more sensitive to differences in brightness than to differences in color, so discarding some color detail is largely imperceptible. Common chroma subsampling ratios include 4:2:0, used in most streaming video, and 4:4:4, which preserves full color information for professional production applications. Subsampling meaningfully reduces bitrate without noticeable quality loss for most viewers.