"Sanctuary" is not a protected term. Any facility can use it, and many that do breed animals, sell them, or offer paid handling experiences — none of which a genuine sanctuary does, because a sanctuary exists to provide lifetime care for animals that cannot be released, not to produce more of them.
This is the single most useful thing to understand before donating to or visiting one. The practical test is accreditation: an external body that inspects against published standards and can withdraw the accreditation.
The Global Federation of Animal Sanctuaries is the main international accreditor, founded in 2007 by leaders including Born Free USA, the Humane Society of the United States and the World Society for the Protection of Animals. Note that it covers wildlife rather than companion cat and dog sanctuaries.
A note on length: This facet lists accreditation bodies and operators we have verified, not every sanctuary organisation. It is deliberately short — we would rather name two we can stand behind than pad the list.