This booklet is one of the booklets in the "Understanding the Atom Series" published by the U. S. Atomic Energy Commission for high school science teachers and their students. Basic information for understanding the laser is provided including discussion of the electromagnetic spectrum, radio waves, light and the atom, coherent light, controlled emission, and the discovery of the laser. Other topics considered include interesting applications, the multitude of lasers, and communications. Numerous photographs and diagrams are utilized and a list of suggested references is included. (PR)