Hue

Hue[h] represents a color in the HSB color space with hue h. 

Hue[h,s,b] specifies colors in terms of hue, saturation and brightness. 

Hue[h,s,b,a] specifies opacity a. 

Hue["string"] returns a color from an HTML color name etc.

Hue[color] returns the HSB representation of color.

Please visit the official Wolfram Language Reference for more details and examples on core symbols.