Bond

In 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 (the coupon) at a later date, termed maturity. Other stipulations may also be attached to the bond issue, such as the obligation for the issuer to provide certain information to the bond holder, or limitations on the behavior of the issuer. Bonds are generally issued for a fixed term (the maturity) longer than ten years. U.S Treasury securities issue debt with life of ten years or more, which is a bond. New debt between one year and ten years is a note, and new debt less than a year is a bill.
A bond is simply a loan, but in the form of a security, although terminology used is rather different. 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. Certificates of deposit (CDs) or commercial paper are considered money market instruments.
In some nations, both bonds and notes are used irrespective of the maturity. Market participants normally use bonds for large issues offered to a wide public, and notes for smaller issues originally sold to a limited number of investors. There are no clear demarcations. There are also "bills" which usually denote fixed income securities with three years or less, from the issue date, to maturity. Bonds have the highest risk, notes are the second highest risk, and bills have the least risk. This is due to a statistical measure called duration, where lower durations have less risk, and are associated with shorter term obligations.
Bonds and stocks are both securities, but the difference is that stock holders own a part of the issuing company (have an equity stake), whereas bond holders are in essence lenders to the issuer. Also 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).