Emily Maitlis explores the phenomenal success of the social networking website in this Money Programme special, including an interview with its co-creator Mark Zuckerberg. Over seven years, Facebook has gained 800 million users and is predicted to be worth $100billion if it is floated on the stock market next year. Emily explores the site's origins and its extraordinary cultural impact, and also questions Zuckerberg on why he believes there is no conflict between sharing and guarding users' personal information