This book provides a comprehensive overview of the most relevant research and standardization results in the area of wireless networking for Industrial IoT, covering both critical and massive connectivity. Most chapters in this book are intended to serve as short tutorials of particular topics, highlighting the main developments and ideas, as well as giving an outlook of the upcoming research challenges. The book is divided into four parts. The first part focuses on challenges, enablers and standardization efforts for reliable low-latency communication in Industrial IoT networks. The next part focuses on massive IoT, which requires cost- and energy-efficient technology components to efficiently connect a massive number of low-cost IoT devices. The third part covers three enabling technologies in the context of Industrial IoT: Security, Machine Learning/Artificial Intelligence and Edge Computing. These enablers are applicable to both connectivity types, critical and massive IoT. The last part covers aspects of Industrial IoT related to connected transportation that are important in, for example, warehouse and port logistics, product delivery and transportation among industries. Presents a comprehensive guide to concepts and research challenges in wireless networking for Industrial IoT; Includes an introduction and overview of such topics as 3GPP standardization for Industrial IoT, Time Sensitive Networking, system dependability over wireless networks, energy-efficient wireless networks, IoT security, ML/AI for Industrial IoT and connected transportation systems; Features contributions by well-recognized experts from both academia and industry.