As nearly every aspect of our society and economy has moved online, vast amounts of digital data are being collected about us-data that spans everything from who we are, to what we like, to who we communicate with, and even what we do. While this mass data collection has some valuable and productive applications, it also poses profound risks. What happens to our basic autonomy as individuals when both the government and private companies can amass detailed profiles about us, using that information to predict and, potentially, manipulate our behavior? What are the implications for our economy when some of the most popular online products and services depend on opaque data collection and personalization? And what does it mean for our democracy when these data practices shape public discourse and influence the flow of news and information?