 This paper provides a comprehensive overview of methods used to estimate evaporation from various sources. It begins with a discussion of the theoretical background of evaporation, including the Penman-Monteath, Priestly-Taylor, and Advectioneridity models. It then moves on to practical applications, covering the estimation of evaporation from open surface waters, lakes, farms, catchments, and irrigated areas. Finally, it concludes with a section on practical considerations, including the use of automatic calculations in commercial weather stations, the use of wind data, and the effects of climate change on evaporation estimates. This article was authored by T. A. McMahon, M. C. Peel, L. Lowe, and others.