This Technical Report gives a classification of modern compressor types and their definitions. This Technical Report presents terms for use in technical and contractual specifications, manufacturer’s literature, information searches and data processing systems, patent information, educational publications for students, service and maintenance instructions, industrial statistics and market surveys, as well as in design, quality, safety, testing and other standards, norms, regulations and codes. It is intended that adequate technical and economical comparison and evaluation of compressor alternatives for specific application conditions be performed with identical functional, mobility, service pressures and service media classes, as well as with equal capacity ratings.