One of the most common uses of bonds is to preserve principal. While this concept works best with bonds that are perceived to be risk-free, like short-term U.S. government
Treasury bills, investors can apply it to other types of bonds as well.
Barring any catastrophic events, bonds are effective in preserving principal. Because bonds are essentially loans with scheduled repayments and
maturities, lenders (bondholders) can expect their bonds to retain value and terminate
at par upon maturity. (For further reading, see
Common Mistakes By Fixed-Income Investors.)