An ecosystem is defined as the living and non-living components in an environment that interact within a specific area. There are many common ecosystem types including savannas, coral reefs, urban areas, deserts, oceans, forests, prairies, rainforests, and tundra. Ecosystems work through the flow of energy and nutrients between organisms in a food chain or food web. However, ecosystems are increasingly threatened by climate change and overexploitation of natural resources.