There are millions of colors at the designer's disposal (16 millions in modern personal computers.) There are almost infinite ways of combining them.

Color can be said to differ in three significant ways: hue, value and saturation.

Hue

Hue is what distinguishes one color from another. In effect it is the generic name for the color - red, say, as opposed to blue.

 

Value

Value, otherwise known as tone, is the relative lightness or darkness of a color. A color with added white is called a tint and a color with added black is called a shade.

Blue from a light to a dark value:

 

Saturation

Saturation, also known as chroma, is roughly equivalent to brightness. Two colors can be of the same hue but be of differing intensities.

Blue from pure saturation to very low saturation (near-gray):