The aim of the book is to address researchers and graduate students at the forefront of study/research on Internet of Things (IoT), by presenting state-of-the-art research together with the current and future challenges in building new smart applications (e.g., Smart Cities, Smart Buildings, and Industrial IoT) in an efficient, scalable, and sustainable way. The book will initially deal with the main pillars of the IoT world (ConnectiInteroperability, Discoverability, and Security/Privacy) with a complete analysis of existing technologies, protocols, and architectures. Covered topics will also involve an overview and a discussion about the integration of IoT technologies with Cloud and Fog Computing paradigms and how this vision will play a fundamental role in the design and deployment of large scale IoT applications. The last part of the book will be entirely dedicated to the application of all the concepts and standards into real world use cases, in order to provide beneficial insights that can be used as design examples and guidelines. It will present the definition of classes of IoT Constrained Devices in terms of Hardware and Software and an experimental analysis related to the creation and deployment of an IoT testbed with heterogeneous devices.