The federal deficit -- the amount by which the government's total budget outlays exceeds its total receipts for a fiscal year -- is estimated at $680 billion for fiscal year 2013. The federal debt -- the sum total of our deficits over the years -- is sitting at about $17 trillion. Meanwhile, some of Silicon Valley's richest and best-known companies are avoiding income taxes by taking deductions related to stock options used to compensate executives. Twitter, which went public on Thursday, is one of them.