IES DG-1-16 describes the proper use of color and illumination in the design of visually functional environments. For most people, the experience of color is only vaguely understood in traditionally accepted terms, and the absence of clear language causes problems. A Universal Color Language was therefore created based on the Munsell Color System. As this Guide explains, the System organizes color into a three-dimensional color arrangement consisting of hue, chroma, and value. Color descriptions in the Universal Color Language can be used to set a standard for a transaction or contract, at an appropriate level of accuracy. This Guide covers the basic principles of color measurement, which involve matching an unknown light with a mixture of three given lights using a visual colorimeter. This Guide also discusses color management, which is helpful to lighting designers who must coordinate their designs with architectural concepts and other plans that are heavily involved with color. It further explains that the esthetics of color can create controversy, and suggests that experience with the effect that color has on people will help designers apply acceptable color schemes and achieve favorable reactions.