For many years, open-source advocates hoped that one day, lots of software would be open source. This goal, which seemed laughable at the time, has (in many ways) come true. When did this happen? Why did this happen? And what does this mean for business? For software developers? For users? In this talk, Allison Randal considers the history and future of the success of open source, discussing the technical, legal, and economic effects that these changes will generate. She argues, among other things, that open source is increasingly a necessity, and that participation in open source is a competitive edge in the modern era.