Saturation determines the change in intensity of pixel colors. Values above 1 will have cause colors to be more vivid, while values below 0 will make colors more dull, eventually reaching grayscale at -1. By default, this value is 0 (no change). Although any float value can be entered for this property, only values in the range [-1, 1] have defined behavior.
Saturation of 0 vs -1:
Saturation of 0 vs 1: