There are several different kinds of government securities. By definition, a government security is any bond issued by a government or its authorities (the Treasury or Social Security, for example) with the promise of repayment upon maturity (usually x number of years after issue), backed by the issuing government. Since these bonds are backed by the federal government, they’re considered to be a relatively low-risk investment.
The most popular kinds of government securities are treasury bonds. The U.S. Treasury issues a couple kinds of government securities. The shortest term options are Treasury bills (commonly referred to as T-bills) which are sold in terms ranging from a couple days up to 52 weeks. The second option is Treasury Notes (T-Notes), that earn interest every six months and are issued in terms of 2, 3, 5, 7, or 10 years. The longest term option is Treasury Bonds, which are issued in terms of 30 years.
For more information on T-bills, Treasury Notes, or Treasury Bonds, visit the .gov links below.