This book provides uptodate coverage of power management in Wireless Sensor Networks i.e. control of transmit power routing, time synchronization, and medium access control (MAC). Detailed work done on least optimum transmission power to maximize the network lifetime while also guaranteeing the best connectivity among the network. The issue of least possible transmit power was taken care of while also considering the data rates and density of deployed nodes. A thorough investigation also on the effects of the transmit power on the nodes and network lifetime thus aiming to prolong the network lifetime by adopting the correct approach. An optimal transmit power is vital for elimination of excessive interference which is also a cause for earlier end of node lifetime.The network deployed should also have a good connectivity to ensure uniform node lifetime. Detailed Research on energy-efficient medium access control(MAC) protocol designed to extend the lifetime of wireless sensor networks.