There are two policies: the lender's policy (mandatory in the US, protects the bank up to the loan amount) and the owner's policy (optional but advisable, protects the buyer up to the purchase price for as long as they or their heirs own the property).
Title insurance is common in the US but rarer in Europe, where Land Registries provide stronger statutory guarantees. In Switzerland, the Grundbuch system is so reliable that title insurance is almost unknown — registered ownership is conclusive.
A US buyer pays a one-time premium of around USD 1,000–2,000 for an owner's title insurance policy on a USD 500,000 home, protecting against any title claim that emerges after closing.