The Illuminating Engineering Society (IES) is an accredited standards development organization under American National Standards Institute (ANSI) approved procedures. The society publishes nearly 100 varied publications including recommended practices on a variety of applications, design guides, technical memoranda, and publications on energy management and lighting measurement, many of which follow the ANSI standards development process. The IES also publishes the most important reference document in the lighting profession, The Lighting Handbook
. It is the industry’s principal source for lighting knowledge.