A mortgage is a transfer of title to real or personal property as security for debt, upon an express condition that upon payment of the debt the transfer shall become null and void. The mortgage may provide for the transfer of possession to the mortgagee subject to the mortgagor's right of redemption. The statutes of different states today provide for the foreclosure of such mortgages, thus preventing the title of the property passing to the mortgagee simply upon failure to pay the debt for which the mortgage was given. Statutes also provide for recording of mortgages especially where the property is to be retained in the possession of the mortgagor. This is to prevent fraudulent transfer and sales of the property in question.

Mortgages of personal property are known as chattel mortgages. Where the goods mortgaged are to remain in possession of the mortgagor, it is necessary to record the chattel mortgage and to renew the same at short intervals in order to secure the right of the mortgagee in the property. Real estate loans are secured either by mortgage or by an instrument known as a trust deed, the main difference between the two being that in the mortgage the conveyance of real property is made directly to the mortgagee with a defeasance clause, while in a trust deed the conveyance is made to a third person to hold in trust until the amount borrowed is repaid and then to reconvey the property back to the mortgagor.