This book aims to introduce recent advances in IoT and its applications for smart environments. The state of the art is reviewed with a focus on the technologies, applications, challenges, and opportunities. At this stage, a comprehensive understanding of the formal and practical applications of IoT in the different scenarios of smart environments is necessary to support future research. Therefore, the main contribution of this book is a comprehensive study of the most recent proposals for smart environments. In addition, this book synthesizes existing information and highlights common threads and gaps that lead to new and complex areas of future research. The book covers a range of major research subjects which will foster future implementations. The topics include smart learning environments, crowdsensing applications, participatory citizen sensing, multimodal perception systems and security challenges. This book seeks to provide a valuable framework for future research projects by expounding the topic to academics, engineers, and industry professionals, which is necessary for the design of future IoT architectures for smart environments.