This two-volume manual is a comprehensive, multidisciplinary guide to understanding the system of digital platforms, or the e-Agorà of the third millennium, making it an essential resource for anyone seeking clarity in the digital world. The handbook brings together the insights of eminent scholars and international experts to explore the legal, ethical, technological, philosophical, economic, and social aspects of platforms. The chapters take a multidisciplinary approach to topics such as AI and its training, data processing and protection, new digital subjects and assets, contract law, provider liability, soft law, and copyright, offering a comprehensive view of the entire digital ecosystem. The authors’ approach fosters a rich interaction among various disciplines, ranging from philosophy to civil law, from computer science to labor law, from industrial property law to public and administrative law, from international law to European Union law, and from economic policy to management. Particular attention is devoted to the European regulatory framework, to the role of artificial intelligence in content creation and decision-making processes, as well as to the implications of platformisation for public procurement and employment relationships. The work also analyzes emerging issues such as algorithmic governance, digital identity, and digital succession, with an in-depth examination of the challenges of co-regulation and the application of current regulations such as the DMA and DSA, alongside the evolving role of national regulatory authorities. It is aimed at researchers and scholars, while also offering essential guidance for professionals and policymakers working to shape the future of digital governance. Volume 1 focuses on the technological, contractual, and legal foundations of digital platforms, offering an in-depth analysis of issues such as liability, intellectual property, and data protection. Volume 2 broadens the perspective to include philosophical, economic, regulatory, and managerial dimensions, providing a holistic understanding of platforms as socioeconomic and political actors.