An animal sanctuary is a facility where animals are brought to live and be protected for the rest of their lives. Unlike animal shelters, sanctuaries do not seek to place animals with individuals or groups, instead maintaining each animal until his or her natural death. In some cases, an establishment may have characteristics of both a sanctuary and a shelter; for instance, some animals may be in residence temporarily until a good home is found and others may be permanent residents. The mission of sanctuaries is generally to be safe havens, where the animals receive the best care that the sanctuaries can provide. Animals are not bought, sold, or traded, nor are they used for animal testing. The resident animals are given the opportunity to behave as naturally as possible in a protective environment.

What distinguishes a sanctuary from other institutions is the philosophy that the residents come first. In a sanctuary, every action is scrutinized for any trace of human benefit at the expense of non-human residents. Sanctuaries act on behalf of the animals, and the caregivers work under the notion that all animals in the sanctuary, human and non-human, are of equal importance.

A sanctuary is not open to the public in the sense of a zoo; that is, the public is not allowed unescorted access to any part of the facility. A sanctuary tries not to allow any activity that would place the animals in an unduly stressful situation.