A bond is just an organization's IOU; i.e., a promise to repay a sum of money at a certain interest rate and over a certain period of time. In other words, a bond is a debt instrument. Other common terms for these debt instruments are notes and debentures. Most bonds pay a fixed rate of interest (variable rate bonds are slowly coming into more use though) for a fixed period of time. Why do organizations issue bonds? Let's say a corporation needs to build a new office building, or needs to purchase manufacturing equipment, or needs to purchase aircraft. Or maybe a city government needs to construct a new school, repair streets, or renovate the sewers. Whatever the need, a large sum of money will be needed to get the job done. One way is to arrange for banks or others to lend the money. But a generally less expensive way is to issue (sell) bonds. The organization will agree to pay some interest rate on the bonds and further agree to redeem the bonds (i.e., buy them back) at some time in the future (the redemption date).