Claims upon property, also known as liens, are legal rights that allow a creditor to take possession of a debtor's property if the debt is not paid. Liens can be placed on real estate, vehicles, or other personal property. They are typically used by banks, creditors, and other lenders to secure repayment of a loan. Liens can also be used by governments to collect unpaid taxes. In some cases, liens can be sold to third parties, allowing them to collect the debt from the debtor.