Rescue archaeology, also known as commercial archaeology, preventive archaeology, salvage archaeology, contract archaeology, developer-funded archaeology, or compliance archaeology, is a state-sanctioned archaeological survey and excavation carried out in advance of construction or other land development. It is a type of field archaeology carried out on sites under threat of destruction, and it is synonymous with the American term "salvage archaeology". The purpose of rescue archaeology is to record a historic site that is under threat from damage or destruction and to preserve the archaeology through recording. The term is largely restricted to North America, South America, Western Europe, and East Asia, especially the United States, Canada, the United Kingdom, Korea, and Japan. Rescue archaeology diverts resources and impacts pre-planned archaeological work, and it must be undertaken at speed. Urban areas with many overlaid years of habitation are often candidates for rescue archaeology. The role of the rescue archaeologist is to rapidly carry out survey and excavation work in areas that are threatened by construction and other development where remains are uncovered or likely to be uncovered. National and municipal laws have created a legitimate environment for the rescue archaeologist, and safety considerations are now carefully measured. Unlike scientific archaeology, rescue archaeology is normally initiated for reasons outside of archaeology itself, and it involves six different entities: the archaeological contractor or organization that undertakes the excavation, the developer, the landowner, the government agency that regulates the excavation, the archaeologist who supervises the excavation, and the public.