An endangered species is a species which has been categorized as very likely to become extinct.Endangered (EN), as categorized by the International Union for Conservation of Nature (IUCN) Red List, is the second most severe conservation status for wild populations in the IUCN's schema after Critically Endangered (CR).

Endangered Species Act of 1973; Other short titles: Endangered Species Act of 1973: Long title: An Act to provide for the conservation of endangered and threatened species of fish, wildlife, and plants, and for other purposes.

ESA Implementation Ensuring an Effective Endangered Species Act. The ESA provides a broad and flexible framework to facilitate conservation with a variety of stakeholders.