Extinction is a part of the natural evolutionary process. As species change, they occasionallybecome better adapted to the environments they live in, while at the same time being altered by that environment. While these species continue their existence, those that cannot adapt to the environment become extinct. However, the common factor in recent extinctions is human damage to natural habitats.

In the Red List created by the International Union for Conservation of Nature (IUCN), only species that have become extinct in the near past are included. In general, the death of the last living member of that species is accepted as the moment of extinction, however, the number of living members necessary for the continuation of the species may have been lost much earlier. There may be cases where it is not known whether a species is completely extinct or not. In this case, the species is considered critically endangered. In addition, in very rare cases, it may be proven that a species thought to be extinct is still alive. In this case, the species enters the category of “Lazarus taxon,” meaning where a species presumed extinct"reappears" after a period of apparent absence.

Endangered species are plant and animal species that are under threat of extinction. They are included in the Red List published every two years by the International Union for Conservation of Nature. For a species to be placed on the Red List, there must be fewer than 50 adult individuals left in the world. Another category is vulnerable species, and for that category, the population of mature individuals must be fewer than 1,000.

The IUCN Red List of Threatened Species is the most comprehensive global inventory of the conservation status of plant and animal species. The IUCN Red List is created by evaluating the extinction risk of thousands of species and subspecies using precise criteria.