Facebook is the hottest company in Silicon Valley. It has gained 800 million users in just seven years and is widely predicted to be worth $100bn if it is floated on the stock market next year. With exclusive access to founder and CEO Mark Zuckerberg and other Facebook bosses, Emily Maitlis examines the Harvard origins of the site and how Facebook wants to make sharing all kinds of digital content easier. She questions Zuckerberg on why he believes there is no conflict between sharing and guarding the personal privacy of Facebook users. Emily examines the strategy behind Facebook's spectacular growth with the company's COO, Sheryl Sandberg. and looks at the advertising system which allows precise demographic targeting based on personal information provided by Facebook users.