The document discusses endangered, rare, and extinct species. It provides definitions for each term: endangered species face a high risk of extinction, rare species have populations of fewer than 10,000 individuals, and extinction occurs when the last member of a species dies. The document notes that over 40% of all living species are at risk of extinction due to threats like habitat loss, invasive species, disease, and climate change. It lists several examples of endangered animal species according to the IUCN Red List.