A viral app is the highest achievement on iTunes and Google Play. It’s an app that customers eagerly share across the Internet, through social networks, email, and word of mouth. It’s like rocket fuel, and it is the best case scenario for an app developer because word of mouth is far more powerful than any paid advertising. Ad clutter is everywhere, and people just ignore it. No one trusts ads, and they cost too much for developers anyway. But humans have shared stories since we’ve been ...