This document discusses endangered species and defines key related terms. It notes that endangered species indicate environmental problems and their protection could benefit both wildlife and humanity. Several factors are listed that can cause a species to become endangered, such as habitat loss, hunting, pollution, disease, and competition from other species. The Endangered Species Act of 1973 aims to protect disappearing plants and animals in the US and elsewhere. Individual actions are suggested that may help endangered wildlife, such as learning about local species, volunteering, and avoiding purchasing illegal or unsustainably-sourced goods.