In finance, a security interest is a legal right granted by a debtor to a creditor over the debtor's property (usually referred to as the collateral) which enables the creditor to have recourse to the property if the debtor defaults in making payment or otherwise performing the secured obligations. One of the most common examples of a security interest is a mortgage: a person borrows money from the bank to buy a house, and they grant a mortgage over the house so that if they default in repaying the loan, the bank can sell the house and apply the proceeds to the outstanding loan.