A mortgage is the transfer of an interest in property (or the equivalent in law - a charge) to a lender as a security for a debt - usually a loan of money. While a mortgage in itself is not a debt, it is the lender's security for a debt. It is a transfer of an interest in land (or the equivalent) from the owner to the mortgage lender, on the condition that this interest will be returned to the owner when the terms of the mortgage have been satisfied or performed. In other words, the mortgage is a security for the loan that the lender makes to the borrower.

This comes from the Old French "dead pledge," apparently meaning that the pledge ends (dies) either when the obligation is fulfilled or the property is taken through foreclosure.

In most jurisdictions mortgages are strongly associated with loans secured on real estate rather than on other property (such as ships) and in some jurisdictions only land may be mortgaged. A mortgage is the standard method by which individuals and businesses can purchase real estate without the need to pay the full value immediately from their own resources. See mortgage loan for residential mortgage lending, and commercial mortgage for lending against commercial property.

The cost to the borrower is measured by the annual percentage rate (APR), which is an effective annual rate of interest and fees paid by the borrower.

In many countries, though not all (Bali, Indonesia is one exception), it is normal for home purchases to be funded by a mortgage. Few individuals have enough savings or liquid funds to enable them to purchase property outright. In countries where the demand for home ownership is highest, strong domestic markets have developed, notably in Ireland, Spain, the United Kingdom, Australia and the United States.

Participants and variant terminology

Legal systems in different countries, while having some concepts in common, employ different terminology. However, in general, a mortgage of property involves the following parties.

Mortgage lender

Mortgagee is a party to whom property is mortgaged, usually a lender. Mortgage provides security to the lender. Given the large sum of money involved in financing a property, a mortgage lender will usually want security for the loan that will provide a claim upon that security and will take precedence over other creditors. A mortgage accomplishes this security.

The lender loans the money and registers the mortgage with the title to the property. The borrower gives the lender the mortgage as security for the loan, receives the funds, makes the required payments and maintains possession of the property. The borrower has the right to have the mortgage discharged from the title once the debt is paid. If the mortgagor fails to repay the loan according to the conditions set forth by the lender, then the mortgagee reserves the right to foreclose on the property.

Borrower

Mortgagor is a party who mortgages property. A mortgagor owes the obligation secured by the mortgage. Generally, the debtor must meet the conditions of the underlying loan or other obligation and the conditions of the mortgage. Otherwise, the debtor usually runs the risk of foreclosure of the mortgage by the creditor to recover the debt. Typically the debtors will be the individual home-owners, landlords or businesses who are purchasing their property by way of a loan.