Color is the subjective response to the objective stimulus of radiant energy of particular wavelength and intensity. Wavelengths determine hue; intensity determines brightness. Color is identified by three methods: (1) verbal description; (2) sample comparison; and (3) physical measurement. The Munsell method of notation accurately describes color in three terms of hue, value (lightness), and chroma (saturation or vividness). The ASTM Standards provide methods for precise identification of color by the Munsell system. The National Bureau of Standards has adopted a standard color terminology used by many industries. Psychological research has provided useful data on color preference and a rational method for color selection. From the behavioral sciences has come the developing technology of psychophysics, which permits measurement of color differences and establishes color tolerances for stated levels of consumer acceptance.