Explore the concept of data externalities in this comprehensive tutorial presented at FAccT 2021. Delve into three case studies, examine the key players involved, and learn where to identify values of privacy. Understand the implications of data sharing, including excessive sharing practices, low reimbursement rates, and data substitutability. Investigate individual contracting and participate in a discussion group focused on enabling collective bargaining. Gain valuable insights from reports of various discussion groups, providing a well-rounded understanding of the complex issues surrounding data externalities in the digital age.