An obligation to repay a sum of money. More specifically, it is funds passed from a creditor to a debtor in exchange for interest and a commitment to repay the principal in full on a specified date. Bonds and other debt instruments have a defined life, a maturity date and normally pay a fixed interest rate or coupon.

See also: Yield, Discount, Par Value, Convertible Bond, Bullet Bond, Fixed Income, Senior Secured Debt, Senior Unsecured Debt,