Pins, badges, stamps, points, and feats: achievement systems are an increasingly important design pattern for the social web. This talk will trace the history of achievements from their roots in videogames through the present day, including a survey of how today’s most visited sites are leveraging them in new and interesting ways. From there, we’ll dive into the psychology of what makes achievement systems so addictive, as well as some theory behind best practices for building them into your own application.