We can define a  mortgage as the transfer of ownership or interest in property to a lender serving to as collateral or security for a loan which is usually for money. The mortgage in itself is not a debt, it is actually the security for the debt promised by the lender. It’s a transfer of an interest in land (or the equivalent) from the ownership of someone to the lender of the mortgage with the promise that this interest will revert back to the original owner when the terms of the mortgage has been fulfilled.