In the current era of pervasive computing and the Internet of Things (IoT), where technology seamlessly integrates into our environment and everyday objects, Wireless Sensor Networks (WSNs) will play increasingly critical roles in several applications and use cases. WSNs find diverse applications in the real world, including monitoring pollution levels in the environment and soil moisture for agriculture, as well as monitoring healthcare patients, traffic, and more. However, the design, optimization, and deployment of such networks face several challenges, including robust architectural design for complex applications, efficient routing, security and privacy of computing and communication, delay minimization, fault tolerance, and maintaining the quality of service in real-time applications. This book presents cutting-edge research and innovative applications in WSNs in various areas such as key management and security, efficiency in routing, machine learning models for dynamic adaptation, and temperature sensing. It is a valuable resource for researchers, engineers, practitioners, and graduate and doctoral students.