With the advances in the technology of microelectromechanical system (MEMS), developments in wireless communications and wireless sensor networks (WSNs) have also emerged. WSNs have become the one of the most interesting areas of research in the past few years. A WSN is composed of a number of wireless sensor nodes which form a sensor field and a sink. These large numbers of nodes, having the abilities to sense their surroundings, perform limited computation and communicate wirelessly form the WSNs. WSNs can be found in a variety of both military and civilian applications worldwide, examples include detecting enemy intrusion on the battlefield, object tracking, habitat monitoring, patient monitoring and fire detection. Sensor networks are emerging as an attractive technology with great promise for the future. However, challenges remain to be addressed in issues relating to coverage and deployment, scalability, quality-ofservice, size, computational power, energy efficiency and security. This book presents important issues of WSNs, from the application, design and technology points of view. The book serves as a comprehensive valuable tool for senior graduate students and scholars who seek to learn latest development in wireless sensor networks.