A wildlife sanctuary, is a naturally occurring sanctuary, such as an island, that provides protection for species from hunting, predation, competition or poaching; it is a protected area, a geographic territory within which wildlife is protected. Refuges can preserve animals that are endangered.
Such wildlife refuges are generally officially designated territories. They are created by government legislation, publicly or privately owned (The area near the Chernobyl nuclear accident site accidentally became a wildlife refuge when it became uninhabitable to humans).
In the United States, the U.S. Fish and Wildlife Service applies the term "refuge" to various categories of areas administered by the Secretary of the Interior for the conservation of fish and wildlife. The Refuge System includes areas administered for the protection and conservation of fish and wildlife that are threatened with extinction, as well as wildlife ranges, game ranges, wildlife management areas, and waterfowl production areas. 
In the 3rd century BC, King Devanampiya Tissa declared the area around Mihintale, Sri Lanka as a sanctuary for wildlife, probably the first of its kind in the ancient world. According to stone inscriptions found in the vicinity, the king commanded the people not to harm animals or destroy trees within the area.
The first American wildlife refuge, Lake Merritt Wildlife Refuge at Lake Merritt, was established by Samuel Merritt and enacted in California state law in 1870 as the first government owned refuge. The first federally owned refuge in America is Pelican Island National Wildlife Refuge and was established by Theodore Roosevelt in 1903 as part of his Square Deal campaign to improve America. At the time, setting aside land for wildlife was not a constitutional right of the president. More recently, a bi-partisan group of US House of Representatives members established the Congressional Wildlife Refuge Caucus to further the needs of the National Wildlife Refuge System in the US Congress.
Today there are several national and international organizations that have taken the responsibility of supervising numerous systems of non-profit sanctuaries and refuges in order to provide a general system for sanctuaries to follow. Among them, the American Sanctuary Association monitors and aids in various facilities to care for exotic wildlife. Their accredited facilities follow high standards and a rigid application processes to ensure that the animals under their care are avidly cared for and maintained.
The wildlife refuge in Brazil has as its objective protecting natural environments where conditions are assured for the existence and reproduction of species or communities of the local flora and the resident or migratory fauna. It can be constituted by private areas, as long as it is possible to make compatible the objectives of the unit with the utilization of the land of the natural resources of the location by the landowners. Public visitation is subject to the conditions and restrictions established by the Management Plan of the unit and to the regulations established by the body responsible for its administration and scientific research depends on previous authorization from the body responsible for the administration of the unit and is subject to the conditions and restrictions established by this body.