Jonah Berger is a professor at the Wharton School of the University of Pennsylvania, internationally bestselling author, and a world-renowned expert on change, word of mouth, viral marketing, social influence, and how products, ideas, and behaviors catch on. He has published over 50 articles in top-tier academic journals, teaches Wharton’s highest rated online course, and accounts of his work often appear in places like The New York Times, Wall Street Journal, and Harvard Business Review. Over a million copies of his books Contagious: Why Things Catch On, Invisible Influence: The Hidden Forces that Shape Behavior, and The Catalyst: How to Change Anyone's Mind are in print in over 35 countries around the world.