Thin film deposition is a process in which the physical characteristics of a surface are improved by applying a very thin coating, often just a few millionths of a millimetre thick.
Thin films are generally used to improve the surface properties of solids.
Transmission, reflection, absorption, hardness, abrasion resistance, corrosion, permeation and electrical behaviour are some of the properties of a bulk material surface that can be improved by using a thin film. Nanotechnology also is based on thin film technology.