The physical basis of color exists in the interaction of light with matter, both outside and inside the eye. The sensation of color depends on physiological activity in the visual system that begins with the absorption of light in photoreceptors located in the retina of the eye and ends with patterns of biochemical activity in the brain. Perceived color can be described by the color names white, gray, black, yellow, orange, brown, red, green, blue, purple, and pink. These 11 basic color terms have unambiguous referents in all fully developed languages. All of these names (as well as combinations of these and many other less precisely used nonbasic color terms) describe.
