Vacuum coatings processes use a vacuum environment and an atomic or molecular vapor source to deposit thin films and coatings. The vacuum environment is used not only to reduce gas particle density but also to limit gaseous contamination, establish partial pressures of gases and control gas flow. Electric power is used to thermally vaporize material, thermally decompose vapors, activate reactive species, generate plasmas and accelerate ions. This paper will trace the development of vacuum technology from the piston water pumps of the Roman Empire, the development of electric power from frictional electricity machines and the electrolytic cell, and the development of deposition techniques based on thermal evaporation, sputtering, arc vaporization, laser ablation and chemical vapor precursors. Both patent and technical literature will be cited as to the first reports on phenomena and processes and the beginnings of sustained applications of various vacuum-coating processes. Several areas of uncertainty will be described and discussed. Often these uncertainties are due to problems with terminology or to the differing nature of patent and technical literature. Several areas where original ("pioneering") work is commonly attributed to an inappropriate individual(s) will be discussed.