When talking about finance, a bond is a debt security in which the authorized issuer owes the holders a debt and is obliged to repay the principal and interest at a later date, commonly called the "termed maturity".

A bond is simply a loan in the form of a security with different terminology: The issuer is equivalent to the borrower, the bond holder to the lender, and the coupon to the interest. Bonds enable the issuer to finance long-term investments with external funds. Note that certificates of deposit (CDs) or commercial paper are considered to be money market instruments and not bonds.

Bonds and stocks are both securities, but the major difference between the two is that stock-holders are the owners of the company (i.e., they have an equity stake), whereas bond-holders are lenders to the issuing company. Another difference is that bonds usually have a defined term, or maturity, after which the bond is redeemed, whereas stocks may be outstanding indefinitely. An exception is a consol bond, which is a perpetuity (i.e., bond with no maturity).