An endangered species is any living organism which is in danger of extinction throughout all or a significant portion its range. The International Union for Conservation of Nature (IUCN) is the international authority on the conservation status of species. IUCN Red List criteria are used to evaluate the extinction risk of thousands of species and subspecies. The IUCN Red List categories include:

- Extinct (EX): No known individuals of the species remain alive.

- Extinct in the Wild (EW): The species survives only in captivity, with no populations remaining in their natural habitats.

- Critically Endangered (CR): The species faces an extremely high risk of extinction in the wild due to few surviving individuals or a rapidly declining population.

- Endangered (EN): The species faces a very high risk of extinction in the wild due to low population numbers or a rapid population decline.

- Vulnerable (VU): The species faces a high risk of endangerment in the wild due to population decline or a restricted range.

- Near Threatened (NT): The species is close to being considered vulnerable but does not currently meet the criteria for EN or VU.

- Least Concern (LC): The species has a wide distribution and no immediate threats to its survival.

- Data Deficient (DD): There is insufficient information to determine the conservation status of the species.

- Not Evaluated (NE): The conservation status of the species has not yet been assessed by the IUCN.

Endangered species face a variety of threats, including habitat loss, poaching, pollution, climate change, and invasive species. Conservation efforts aimed at protecting and restoring their habitats, reducing hunting and illegal trade, and raising awareness about their plight are essential for their survival.