WSN (Wireless Sensor Network) is composed of a large number of small, inexpensive, energy constrained nodes that are used to sense data for various civil and military applications. The sensed data from the environment is then propagated using various routing techniques to the base station. A sensor node becomes useless once its energy source i.e. the battery gets used up. To increase network lifetime, the main issue in wireless sensor networks is of energy conservation due to the fact that sensor nodes are kept in conditions and places that are inaccessible and left unattended.