Why does the problem of data privacy remain so intractable? Deep Dark Data explores how this contemporary problem begins with the ways we define and use personal data. Instead of debating how best to protect personal data, Alison Cool argues that we would be better off asking how data became personal in the first place. Drawing on years of ethnographic research in Sweden, the most datafied country in the world, Cool reveals that what we call personal data encapsulates a number of very different relations between data and persons, none of which are inherent in the data itself. This surprising and highly original book untangles these relations and traces their troubled histories, ultimately inviting us to understand privacy as a gendered and racialized politics of moral exclusion.