Let’s think back for a moment to the early days of Facebook. Today, the social media giant boasts more than a billion users worldwide, but there was a time when its base was just an infinitesimal fraction of that number—a handful of early adopters scattered across American college campuses. Pretty quickly, that handful, having influenced others to join up, grew to a critical mass. People across the world felt that they had to be on Facebook because their friends were already using it, and the more users joined, the more attractive the social networking site seemed to potential users. This quickly reached a tipping point and led to the explosion of users that they’ve seen in the past few years.