A mortgage is a method of using property (real or personal) as security for the payment of a debt.

The term mortgage (from Law French, lit. death vow) refers to the legal device used in securing the property, but it is also commonly used to refer to the debt secured by the mortgage.

In most jurisdictions mortgages are strongly associated with loans secured on real estate rather than other property (such as ships) and in some cases only land may be mortgaged. Arranging a mortgage is seen as the standard method by which individuals or businesses can purchase residential or commercial real estate without the need to pay the full value immediately.

In many countries it is normal for home purchase to be funded by a mortgage. In countries where the demand for home ownership is highest, strong domestic markets have developed, notably in Great Britain, Spain and the United States.