When the SCION project started in 2009, the goal was to create an architecture offering high availability and security for basic point-to-point communication. In the five years since the publication of SCION: A Secure Internet Architecture, this next-generation Internet architecture has evolved in terms of both design and deployment. On the one hand, there has been development of exciting new concepts and systems, including a new global time-synchronization system, an inter-domain approach for bandwidth reservations called COLIBRI, and Green Networking, which allows combating global climate change on three fronts. On the other hand, SCION is now also in production use by the Swiss financial ecosystem, and enables participants such as the Swiss National Bank, the Swiss provider of clearing services (SIX), and all Swiss financial institutes to communicate securely and reliably with each other via the Secure Swiss Finance Network. This unique guidebook provides an updated description of SCION's main components, covering new research topics and the most recent deployments. In particular, it presents in-depth discussion of formal verification efforts. Importantly, it offers a comprehensive, thorough description of the current SCION system:Describes the principles that guided SCION's design as a secure and robust Internet architectureProvides a comprehensive description of the next evolution in the way data finds its way through the InternetExplains how SCION can contribute to reducing carbon emissions, by introducing SCION Green NetworkingDemonstrates how SCION not only functions in academic settings but also works in production deploymentsDiscusses additional use cases for driving SCION's adoptionPresents the approaches for formal verification of protocols and code Illustrated with many colorful figures, pictures, and diagrams, allowing easy access to the concepts and use cases Assembled by a team with extensive experience in the fields of computer networks and security, this text/reference is suitable for researchers, practitioners, and graduate students interested in network security. Also, readers with limited background in computer networking but with a desire to know more about SCION will benefit from an overview of relevant chapters in the beginning of the book.