This paper gives a survey of materials suitable for the preparation of dielectric films for interference coatings, highly reflecting metallic films, and semitransparent coatings for neutral density filters and sunglasses. It is shown that improved vacuum-deposition techniques and treatments, such as evaporation by electron bombardment, film deposition under ultrahigh vacuum conditions and at extremely high rates, reactive evaporation in an oxygen atmosphere, and ultraviolet irradiation after the film deposition, have greatly increased the number and improved the quality of film materials for optical applications. The most important factors for producing dielectric films with high transmittance and metallic coatings with high reflectance are discussed. Coatings suitable for controlling the temperature of satellites and space vehicles are described.