You can measure a bond's value, or what it's worth, in at least three different ways.
The
market value
of a bond, which is the price at which it's bought or sold, changes constantly during the bond's term, although its par value remains fixed, usually at $1,000. Those price changes are the result of a changing combination of:
External forces, such as interest rates
The bond's term
The economic strength of the issuer, reflected in the bond's rating
