Megabrands like Dropbox, Instagram, Snapchat, and Airbnb were barely a blip on the radar years ago, but now they're worth billions--with hardly a dime spent on traditional marketing. No press releases, no TV commercials, no billboards. Instead, they relied on growth hacking to reach users and build their businesses. Growth hackers have thrown out the old playbook and replaced it with tools that are testable, trackable, and scalable. They believe that products and businesses should be modified repeatedly until they're primed to generate explosive reactions. Bestselling author Ryan Holiday, the acclaimed marketing guru for many successful brands, authors, and musicians, explains the new rules in a book that has become a marketing classic in Silicon Valley and around the world. This new edition is updated with cutting-edge case studies of startups, brands, and small businesses.