The International Union for Conservation of Nature and Natural Resources (IUCN) has published the IUCN Red List of threatened species. The objectives of this list are:

·         Identification and documentation of endangered species

·         Creating awareness about the importance of threatened species

·         Preparing a global index for the decline of biodiversity

This list categories various species according to the degree of threat   which they face. Various categories of IUCN red list species are as follows:

Extinct: - When there is no reasonable doubt that the last individual of that species has died, the species is referred to as extinct.

Extinct in the wild: - When exhaustive surveys fail to record an individual in the known or expected habitat, the species is referred to as extinct in the wild.

Critically endangered: - When a species is facing extremely high degree of risk of extinction in the immediate future.

Endangered: - When a species is facing high risk of extinction in the wild in the near future.

Vulnerable: - When a species is prone to extinction but not in the immediate future it is referred to as vulnerable species     

Lower Risk: - When a species is facing very low degree of threat of extinction then it is called lower risk species.

Data deficient: - When there is inadequate data to make a direct or indirect assessment of the risk of extinction then the species is referred to as data deficient species.

Not evaluated: - The species which has not been assessed

Example of endangered species are Tiger, Asian Lion, Tortoise, Black rhinoceros, Black Buck, Green sea turtle, Red Panda and Siberian white crane.