We live in a world where a tweet can be instantly retweeted and read by millions around the world in minutes, where a video forwarded to friends can destroy a political career in hours, and where an unknown man or woman can become an international celebrity overnight. Virality: individuals create it, governments fear it, companies would die for it. So what is virality and how does it work? Why does one particular video get millions of views while hundreds of thousands of others get only a...