Imperial ambitions

NOT since the era of imperial Rome has the "thumbs-up" sign been such a potent and public symbol of power. A mere 12 years after it was founded, Facebook is a great empire with a vast population, immense wealth, a charismatic leader, and mind-boggling reach and influence. The world's largest social network has 1.6 billion users, a billion of whom use it every day for an average of over 20 minutes each. In the Western world, Facebook accounts for the largest share of the most popular activity (social networking) on the most widely used computing devices (smartphones); its various apps account for 30% of mobile internet use by Americans. And it is the sixth-most-valuable public company on Earth, worth some 325 billion.