Federal Debt 101.
http://links.govdelivery.com/track?type=click&enid=ZWFzPTEmbWFpbGluZ2lkPTIwMTMwMTI1LjE0ODE2NTExJm1lc3NhZ2VpZD1NREItUFJELUJVTC0yMDEzMDEyNS4xNDgxNjUxMSZkYXRhYmFzZWlkPTEwMDEmc2VyaWFsPTE3MzY4MzEyJmVtYWlsaWQ9amltdGFrZWRhQGdtYWlsLmNvbSZ1c2VyaWQ9amltdGFrZWRhQGdtYWlsLmNvbSZmbD0mZXh0cmE9TXVsdGl2YXJpYXRlSWQ9JiYm&&&100&&&http://www.gao.gov/special.pubs/longterm/debt/debtbasics.html