In the HSB color space:
Three numbers representing Hue, Saturation, and Brightness can be used to uniquely identify each color in the spectrum.
Hue is what we usually refer to informally as "color". For example, Red, Orange, Yellow, Green, Cyan, Blue, and Violet are all different hues.
Saturation refers to vividness or deepness of a color. For example, a deep fire engine red is very saturated, while a pale pink, which may have the same hue, is very unsaturated. When all of the saturation is removed from a color, it becomes gray.
Brightness refers to the lightness or darkness of a color.
Using this model, you can select a color according to its perceived intensity, lighter or darker color.