A colour's saturation is a measure of its colourfulness. The level of saturation tells, how much of a spectrum colour is present in a colour.

Black, shades of grey and white are achromatic, their saturation is 0. The more a colour tends towards grey, the less saturation.

Saturation, in collaboration with lightness and hue specify a colour.

Saturation is also a term used in photography, where you can influence the colours' saturation using skylight filters or polarizing filters.