The present book is written for those researchers who are interested in designing a low-cost, low- power Wireless Sensor Network (WSN). In this book, design and development of a low cost WSN node using MSP430 microcontroller and nRF24L01 radio transceiver has been given in detail. A new adaptive power algorithm has been developed, which further reduces the power consumption of this node. The evaluation of WSN node has been done for various tests including routing algorithms, packet loss measurement, receiver sensitivity and calculation of free space loss. A case study of Car Parking Management System has been described as a practical application of WSN. The developed WSN has potential applications in the fields of military surveillance, seismic detection, environmental monitoring, underground coal mine and medical instrumentation.