Restoration ecology is the scientific study supporting the practice of ecological restoration, which is the practice of renewing and restoring degraded, damaged, or destroyed ecosystems and habitats in the environment by active human interruption and action. Effective restoration requires an explicit goal or policy, preferably an unambiguous one that is articulated, accepted, and codified. Restoration goals reflect societal choices from among competing policy priorities, but extracting such goals is typically contentious and politically challenging. Natural ecosystems provide ecosystem services in the form of resources such as food, fuel, and timber; the purification of air and water; the detoxification and decomposition of wastes; the regulation of climate; the regeneration of soil fertility; and the pollination of crops. These ecosystem processes have been estimated to be worth trillions of dollars annually. There is consensus in the scientific community that the current environmental degradation and destruction of many of Earth's biota are taking place on a "catastrophically short timescale". Scientists estimate that the current species extinction rate, or the rate of the Holocene extinction, is 1,000 to 10,000 times higher than the normal, background rate. Habitat loss is the leading cause of both species extinctions and ecosystem service decline. Two methods have been identified to slow the rate of species extinction and ecosystem service decline, they are the conservation of currently viable habitat and the restoration of degraded habitat. The commercial applications of ecological restoration have increased exponentially in recent years. In 2019, the United Nations General Assembly declared 2021–2030 the UN Decade on Ecosystem Restoration. Definition Restoration ecology is the academic study of the process, whereas ecological restoration is the actual project or process by restoration practitioners. The Society for Ecological Restoration defines "ecological restoration" as an "intentional activity that initiates or accelerates the recovery of an ecosystem with respect to its health, integrity and sustainability". Ecological restoration includes a wide scope of projects including erosion control, reforestation, removal of non-native species and weeds, revegetation of disturbed areas, daylighting streams, the reintroduction of native species (preferably native species that have local adaptation), and habitat and range improvement for targeted species. For many researchers, the ecological restoration must include the local communities: they call this process the "social-ecological restoration". E. O. Wilson, a biologist, stated, "Here is the means to end the great extinction spasm. The next century will, I believe, be the era of restoration in ecology." History Restoration ecology emerged as