Optical coatings modify the reflectance, transmittance, and absorptive properties of optic substrates to make them much more efficient and functional. From an optical manufacturer's perspective, there are several pertinent pieces of information that need to be communicated when specifying optical coatings. This video addresses topics, such as glass type, wavelength, transmission or reflection requirements, angle of incidence. We also address supplemental requirements, such as witness piece requirements, special documentation, environmental durability requirements, and laser damage requirements.