Saturation

The control moves every colour by the same amount, and that is what separates it from vibrance. Vibrance lifts the muted colours while leaving strong colours and skin tones roughly where they were, which makes it the gentler tool on a flat image. Pushed hard, saturation clips the colour channels, so the detail inside a red jumper or a sunset collapses into a flat block and faces go orange before anything else does. The frequent mistake is reaching for it when the real problem sits elsewhere. An image that looks dull is very often short of contrast or wrongly white balanced.