The first WhatsApps weren’t WhatsApps. In the spring of 2009, Jan Koum, a thirty-three-year-old computer programmer, was trying to get people interested in a product he had developed for Apple’s App Store, which had opened the previous summer. Koum tweaked his app’s name every few days—from Status App to Smartphone Status to iPhone Status—so that it would appear among the newest releases. The idea was that the app would show people what their contacts were doing before they called or messaged th...