Saturation
The intensity or purity of a colour, from fully neutral grey to the most vivid version available.
Measured in
%
In depth
A saturation control scales every colour by the same proportion, which is why it is so easy to overdo: colours that were already strong clip first, losing their internal detail while weaker colours have barely moved. Skin tones sit at low saturation and are damaged quickly, which is the main argument for using vibrance instead.
Examples in practice
Pushing global saturation to make a sky bluer turns skin orange and destroys the gradation in a red jacket.