Saturation is the intensity of a color. In CSS HSL notation, it is the second value and is written as a percentage: 100% gives a vivid color, while 0% removes the color and produces a shade of gray. section 11.2.2
Reading an HSL color
The color hsl(198deg 73% 46%) has a cyan-blue hue, fairly high saturation, and lightness near 50%. It appears as a rich blue, a little darker than sky blue, and is equivalent to #2097c9. Unlike the hex value, the HSL value makes its intensity easier to identify. section 11.2.2
Read saturation alongside hue and lightness: hue identifies the position on the color circle, while lightness controls how light or dark the result is. HSL colors are limited to the sRGB gamut. section 11.2.2
