• The IUCN Red List of Threatened Species (also known as the IUCN Red List or Red Data List), founded in 1964, has evolved to become the world’s most comprehensive inventory of the global conservation status of biological species.
• It uses a set of criteria to evaluate the extinction risk of thousands of species and subspecies.
• These criteria are relevant to all species and all regions of the world. With its strong scientific base, the IUCN Red List is recognized as the most authoritative guide to the status of biological diversity.
• A series of Regional Red Lists are produced by countries or organizations, which assess the risk of extinction to species within a political management unit.
• The IUCN Red List is set upon precise criteria to evaluate the extinction risk of thousands of species and subspecies. These criteria are relevant to all species and all regions of the world. The aim is to convey the urgency of conservation issues to the public and policy makers, as well as help the international community to try to reduce species extinction.
• According to the International Union for Conservation of Nature (IUCN) (1996), the formally stated goals of the Red List are (1) to provide scientifically based information on the status of species and subspecies at a global level, (2) to draw attention to the magnitude and importance of threatened biodiversity, (3) to influence national and international policy and decision-making, and (4) to provide information to guide actions to conserve biological diversity.

Species are classified by the IUCN Red List into nine groups, specified through criteria such as rate of decline, population size, area of geographic distribution, and degree of population and distribution fragmentation.

• Extinct (EX) – No known individuals remaining
• Extinct in the wild (EW) – Known only to survive in captivity, or as a naturalized population outside its historic range
• Critically endangered (CR) – Extremely high risk of extinction in the wild
• Endangered (EN) – High risk of extinction in the wild
• Vulnerable (VU) – High risk of endangerment in the wild
• Near threatened (NT) – Likely to become endangered in the near future
• Least concern (LC) – Lowest risk (Does not qualify for a more at-risk category; widespread and abundant taxa are included in this category.)
• Data deficient (DD) – Not enough data to make an assessment of its risk of extinction
• Not evaluated (NE) – Has not yet been evaluated against the criteria

In the context of the IUCN Red List, “threatened” embraces the three categories of Critically Endangered, Endangered, and Vulnerable.