[This is preliminary documentation and subject to change.]
Color can be described in terms of components. The components most often used by imaging professionals are hue, saturation, and brightness. A hue is what we normally think of as a color. A color's hue fixes its place in the visible spectrum of light. The saturation of a color is how "pure" or "strong" a color is. Neutral gray is said to have zero saturation. The brightness of a color refers to the intensity of light that is reflected or transmitted by an image.
The terms tint, tone, and shade are also well-used in color imaging literature. A tint of a color is obtained by mixing its hue with white. A tone of a color is created by mixing a hue with gray. A shade of a color is made by adding black to its hue.