A property right can be used to guarantee the performance of a personal obligation. Suppose A borrows a sum of money from B. B has a contractual right to repayment, but an additional guarantee of performance can be provided using A's property. For example A might give possession to B of some property belonging to A, agreeing that B has the right to keep possession of that property until the debt is paid, and perhaps to sell it and use the proceeds to satisfy the debt if A fails to pay.
Security interests based on property rights are called real securities. Depending on the property right involved, and the agreed powers of the creditor, such arrangements are variously called mortgages, pledges, liens or charges. These security interests are described in more detail later in this module. Example: D, a mechanic, repairs a car belonging to C. When C comes to collect his car, D refuses to return it until C pays the bill.