A contract representing a loan that an individual makes to the U.S. government. The government repays the loan after a set period of time with a set interest rate. Because savings bonds are backed by the full faith and credit of the U.S. government, they are a safe way of saving. There are two types of savings bonds: Series EE bonds are issued for 30 years and a bondÂ’s value increases as the interest earned is added to the principal; Series HH bonds are current income securities issues for 20 years, which includes a 10-year original maturity period and a 10-year extension.