The 1994 International Union for Conservation of Nature (IUCN) "Red List", compiled by the World Conservation Monitoring Centre, included more than 6,000 animal species known to be at risk. Since then, further updating added numerous species to the list of endangered species at risk of extinction.
Endangered species are listed in IUCN's "Red List" as follows:
Extinct (EX): there is no reasonable doubt that the last individual has died.
Extinct in the Wild (EW): it is known only to survive in cultivation, in captivity or as a naturalized population (or populations) well outside the past range.
Critically Endangered (CR): facing an extremely high risk of extinction in the wild.
Endangered (EN): facing a very high risk of extinction in the wild.
Vulnerable (VU): facing a high risk of extinction in the wild.
Near Threatened (NT): is likely to qualify for a threatened category in the near future.
Least Concern: widespread and abundant.
Data Deficient (DD): inadequate information to make a direct, or indirect, assessment of its risk of extinction.
Not Evaluated: it has not yet been evaluated against the criteria.