This book is about the fundamentals of the Internet of Things (IoT). It comprises of the overall architecture of IoT, a comparison with M2M. The book highlights the various areas where IoT is implemented, real IoT examples, and applications. The book is also focused on IoT communication technology, sensors, wireless network communication and protocols, hardware, along with IoT systems, and networks. At last, the book also highlighted some important aspects of IoT security which include threat scenarios. This book will expose the fundamentals of IoT, which will be helpful for IoT learners, technology enthusiasts, specialists, software developers, scientists, Ph.D. scholars, and researchers.