Can interest rate of a bond issued by companies change?

[SuperDavid]

im reading an investment book, there is this idea of Macaulay Duration, which is said to measure a bond's sensitivity to "interest rate changes". if a bond's interest rate can't change, what does this duration mean?

 

[RalphC]

A corporate bond is a fixed rate, say 6% and is issued for a certain period of time, let's say 30 years. If you hold that bond, you will receive 6% per year and then at the end of 30 years you will get the face value of the bond back. Bond prices refer to the secondary market for bonds - almost no one holds bonds for all 30 years, they buy and sell them like stocks. So if you bought a new bond today for $1,000 with an interest rate of 5% and next month the Fed increases interest rates so new bonds selling next month would need to yield 5.5%, the price of the bond you hold with 5% interest will decrease - should you want to sell the bond in the secondary market.