Fixed income securities, also known as bonds, are loans that are usually taken out by a government or company. They normally pay bondholders a set rate of interest over a given time period, at the end of which the amount borrowed, the principal, is repaid by the bond issuer. The regular interest payments, which are known as coupons, can provide investors with a predictable income stream over the life of the bond, until it matures. The price of a bond can vary over its life, meaning investors can also profit from any increase in its value if they sell before maturity.