The Endangered Species Act of 1973 aims to protect and recover imperiled species and the ecosystems they depend on. It defines endangered species as those in danger of extinction throughout all or a significant portion of their range, and threatened species as those likely to become endangered in the foreseeable future. The U.S. Fish and Wildlife Service is responsible for identifying species as endangered or threatened and writing and implementing recovery plans with various stakeholders. The ESA prohibits taking listed animals and trading in listed plants and animals, and requires designation of critical habitats for listed species.