1. <graphics> In colour theory, the "colourfulness" of a stimulus relative to its brightness, the amount of the dominant wavelength relative to other wavelengths in the colour, one of the three coordinates in the hue, saturation, value (HSV) and hue, saturation, brightness (HSB) colour models.
White, black and grey contain equal amounts of red, green and blue light and are completely unsaturated. A pure colour with very little gray in it is highly saturated. The amount of saturation does not affect the hue of a colour and is unrelated to the value (total amount of light in a colour).
There are several competing mathematical definitions of saturation.
2. The state of any system that is operating at its maximum capacity, e.g. a network connection that is carry a continuous stream of data with no idle time. Capacity planning aims to monitor load and increase resources before saturation is reached.