Glow Discharge Optical Emission Spectrometry (GDOES) is a relatively new technique for the quantitative analysis and depth-profiling of solids. The basic principles of the operation of the instrument are described, as well as the current theories on sputtering and quantitative analysis necessary for a fuller understanding of the technique. Its capabilities and some of its limitations are described along with some of the author's experience in its use. A wide range of applications are reviewed both in the bulk analysis of metals, polymers and powders, and in the depth-profiling of metal alloy coatings, polymers, glasses and ceramics. The emphasis is on applications in industry, particularly in the coatings industry, where the speed, accuracy and sensitivity of the technique have gained for GDOES a strong and growing niche.