On February 1, Facebook filed for an I.P.O. (Initial Public Offering), taking the first measure towards becoming a publicly traded company.  Facebook is aiming to raise $5 billion from its I.P.O., which, according to The Economist, would give it market capitalization (total value of tradable shares) similar to that of McDonald's.  Mark Zuckerberg, Facebook's founder and CEO, owns 28% of the company, which will be worth approximately $28 billion.  Facebook's high value is due in large part to its ability to target individuals with advertisements which pertain to their particular interests.