HWB is a new color standard in CSS3. It was founded by the same person who had invented HSL. The aim was to make it easier to use. It is. Unfortunately, it’s a working draft yet.
HWB includes Hue, Whiteness, and Blackness.
Hue
If you use HSL, you must be familiar with Hue. It is composed of rainbow colors: starting with red and ending with violet. From violet, it returns to red, making 360 degrees. Hue specifies an angle starting at 0 with red.
Whiteness and Blackness
In contrast with HSL, in HWB, to reach the desired colors, you should specify the hue and leave Whiteness and Blackness to zero. It’s quite easy to use: black is too dark, and white is too light. The more black you add, the darker your desired color will be. In case you add as much white as you add black, your final color will appear grey.