This insightful book provides a timely review of the potential threats of advertising technologies, or adtech. It highlights the need to protect internet users not only from privacy risks, but also as consumers and citizens online dealing with a highly complex technological setting. Jiahong Chen illustrates a concise overview of the technical, economic and legal aspects of adtech together with coverage of other important areas. These include: the ongoing debates around online advertising and data protection, an up-to-date analysis of the application of the GDPR, and insights into both the practices and theories of the regulation of data protection law. The book provides a clear picture of what is truly at stake with online advertising practices, concluding with a critical assessment of the current regime and a proposed approach to reform data protection laws. This book will provide essential reading for researchers and law students requiring an overview of the legal framework and current practices, alongside legal practitioners and policymakers evaluating the benefits and risks of data-driven technologies.