The parties in guarantees refer to the people or entities that have to fulfill obligations in the agreement. In many cases, the obligation is paying back loaned money. The parties in a personal or corporate guarantee are:
The lender: the person to whom an obligation is owed (like the payment of money)
The debtor: the person who has to perform the obligation (pay back the lender)
The guarantor: the person who agrees to perform the obligation (take over the loan payments) if the person who is supposed to do so (the debtor) fails to perform