This chapter discusses the implications of datafication, the process by which more and more aspects of life and society are being turned into data. The author argues that data is a material produced by abstracting our life and world, and that as more and more aspects of life and society depend on data-driven processes, we live in an era of datafication. The author also highlights that working with design means enabling, reforming or potentially resisting that process. The author also emphasizes that data as a material in data-driven systems and services should be approached as a socio-material and technical condition that creates and systematizes data, and that asking what data will and should represent, helps designers approach the people represented in data not as objects, but as subjects with an own mind and agency in the becoming of data.