Wireless Sensor Network finds its applications in various streams where human intervention becomes impossible. Recently the application is extended with IoT. Still there are more research challenges in WSN. One such major challenge is energy conservation of the network. Energy conservation can be achieved through increased efficient energy use, in conjunction with reduced consumption from conventional energy sources. Energy-aware routing is one such attempt to extend the life of a WSN at network layer. This book gives a brief idea of various energy aware routing protocol techniques for WSN. It also deals with different approach for calculating the cost of link between any two sensor nodes, using fuzzy logic and conventional neural network. It is sure that the knowledge gathered through these techniques will add to the development of advanced algorithms and applications.