What is the Federal Debt and How Does the Debt Limit Work?

From the USA.gov Blog:
At the end of fiscal year 2011, the federal debt totaled $14.8 trillion.
The debt limit determines when the U.S. Department of Treasury can or cannot borrow money to cover the country’s debts.
Learn more about the federal debt and the debt limit in Federal Debt 101, from the Government Accountability Office.