The responsibility of a person to pay a debt or other financial obligation. If an individual signs a promissory note, that individual usually has full personal liability for the debt. An exception is the unusual situation of a non-recourse individual loan, in which the lender agrees to look only to the collateral for recovery in the event of default.

A formal promise by one party (the guarantor or surety) to another party (the creditor) to accept responsibility of a third party’s (the principal debtor) debt, if that third party cannot or refuses to pay it.