As with any investment, bonds have risks, such as default risk and reinvestment risk.
Bonds can provide a predictable income stream because they generally pay bondholders interest twice a year. They're also useful for preserving capital because they promise to repay the original loan amount upon maturity. As with any investment, bonds have risks, such as default risk and reinvestment risk. Bonds tend to be less volatile than stocks, but an issuer potentially could default on its loan or (in the case of a callable bond) call the loan (this is when an issuer returns the principle and stops interest payments before the bond matures).