To learn about bonds, visit www.investinginbonds.com, a site created by the Bond Market Association, which represents bond underwriters and dealers. This site also provides price quotes for actively traded bonds, which you can use to see if the price your broker for a bond is fair.
To learn about and purchase U.S. savings bonds online, go to
http://www.savingsbonds.gov/. This site has a bond calculator that lets you find out how much your savings bond is worth today, whether it's still earning interest and if so, at what rate. You can also keep an inventory of your bonds and see their current value by using its Savings Bond Wizard.