The IUCN Red List of Threatened Species The IUCN Red List of Threatened Species is the most comprehensive list of the current state of conservation of plant and animal species in the world, compiled and maintained by the International Union for Conservation of Nature (IUCN) since 1963.

The IUCN Red List has been recognized as the most authoritative guide to the status of biodiversity. The IUCN Red List is recognized as the most authoritative indicator of biodiversity status, and the main species assessment organizations are IUCN, the World Conservation Monitoring Center, and expert groups within the IUCN Species Survival Commission. In total, these groups have assessed nearly half of the species on the Red List.

Species in the Red List of Endangered Species are classified into nine classes, based on criteria such as rate of population decline, total number of species, geographic distribution, and community dispersal: extinct, extinct in the wild, critically endangered, endangered, vulnerable, near vulnerable, no vulnerable, lack of data, and for assessment.

The IUCN Red List is based on strict criteria to assess the risk of extinction of thousands of species and subspecies.