Abstract: Quercus L. is a huge woody genus with about 423 species. As the backbone tree species of forests in the northern hemisphere, oak trees have important ecological values such as carbon sequestration, water conservation, and animal habitats, as well as utility values such as timber, firewood, and industrial raw materials. In recent years, research on oaks has been exceptionally active, with many review papers, but mostly are regional or scientific problem oriented reviews, and there are few comprehensive reviews at a global scale. This review provides a synopsis and annotation of oak classification, geographical distribution, tree species and forest resources, ecological and utility value, and the diversity conservation. The main contributions are listed as follows: the latitude distribution range of the genus in the eastern and western hemisphere was sorted out to be 0~60°N and 1~50°N, respectively; The data of annual mean temperature and precipitation in the distribution areas for 39 important oak species worldwide were provided; Scientific data on global oak forest resources, value, and industry were thoroughly provided here; Emphasis was placed on oak genomes, ancient tree resources, species and ecosystem red lists, as well as the conservation strategies. This review provides important references for frontline engineering and technical personnel engaged in the cultivation, protection, and utilization of oak forests, as well as assistance for professionals from different disciplines.