This book describes the development of astronomy in the Extreme Ultraviolet (EUV) wavelength range, from the first rocket-based experiments in the late 1960s through to the latest satellite missions. It provides detailed material on the tools of EUV astronomy, dealing with the instrumentation, observational techniques, and modelling tools for the interpretation of data. Prospects for future EUV missions are discussed, and a catalog of known EUV sources is included.