Emergence is what happens when an interconnected system of relatively simple elements self-organizes to form more intelligent, more adaptive higher-level behavior. It's a bottom-up model rather than being engineered by a general or a master planner, emergence begins at the ground level. Systems that at first glance seem vastly different--ant colonies, human brains, cities, immune systems--all turn out to follow the rules of emergence. In each of these systems, agents residing on one scale start producing behavior that lies a scale above them: ants create colonies, urbanites create neighborhoods. Author Steven Johnson takes readers on an eye-opening intellectual journey from the discovery of emergence to its applications. He introduces us to our everyday surroundings, offering surprising examples of feedback, self-organization, and adaptive learning. Drawing upon evolutionary theory, urban studies, neuroscience, and computer games, Emergence is a guidebook to one of the key components of twenty-first-century culture. Until recently, Johnson explains, the disparate philosophers of emergence have worked to interpret the world. But today they are starting to change it. This book is the riveting story of that change and what it means for the future.