A loan (qardh) is a fungible item (including money) that is transferred from one party (the lender) to another (the borrower), with the understanding that the latter will return it to the former at some future date. A loan, thus, arises only through a loan contract (aqd al-qardh). On the other hand, a debt (dayn) is any liability that arises when settlement is deferred to the future. An example is the deferred price or unsettled price in in a contract of sale (ba’i). Likewise, an unpaid rental (ujrah or badal) in a contract of lease (aqd ijarah) constitutes a deb.

Debt is more comprehensive than loan: every loan is a debt, but not vice versa. Not all debts originate from loans, but all loans are necessarily debts. Debts originate for several reasons including when a person lends an amount of money to another. However, loans arise only when an amount of money (or any fungible item) is lent.