The ebook edition of this title is Open Access and freely available to read online.The Internet of Things (IoT) is rapidly transforming our world, connecting billions of devices and enabling unprecedented levels of automation, data exchange, and convenience. From smart homes and wearable fitness trackers to industrial sensors and connected cars, IoT devices are permeating every aspect of our lives. However, this widespread adoption has also introduced significant security challenges that must be addressed to ensure the safety and privacy of individuals and organizations.The ERATOSTHENES project, funded by the European Commission, rises to meet these challenges by developing a novel Trust and Identity Management Framework for IoT devices. This framework takes a holistic approach to IoT security, considering the entire lifecycle of devices from initial deployment to decommissioning. Designed to be distributed, automated, auditable, and privacy-respectful, the ERATOSTHENES framework empowers users with control over their data and strengthens trust and resilience within the IoT ecosystem. By leveraging cutting-edge technologies like blockchain, advanced cryptography, and machine learning, ERATOSTHENES provides a comprehensive suite of security mechanisms to address the evolving threats and vulnerabilities in the IoT landscape.This book dives into the territory of the ERATOSTHENES project, providing a detailed exploration of its technical architecture, implementation, and real-world applications. It examines the key challenges addressed by the project, including the heterogeneity of IoT devices, the management of device identities, and the protection of user privacy. The book also highlights the innovative solutions developed within ERATOSTHENES, such as the Trust Manager & Broker, the Self-Sovereign Identity system, and the Advanced Data Protector. Furthermore, it showcases the practical implementation of these and other research solutions and outcomes through pilot projects in diverse domains, including connected vehicles, remote patient monitoring, and industrial network security.This book serves as a valuable resource for researchers, practitioners, and policymakers seeking to understand and address the complex security challenges of the IoT. It offers insights into the latest advancements in IoT security technologies and provides a roadmap for building a more secure and trustworthy IoT ecosystem.