Wireless Sensor Network (WSN) is used in many applications like in military, environmental monitoring, traffic, security, industrial sensing, intelligent homes, context aware computing, power grid, infrastructure protection etc. In every application of wireless sensor network, energy is a scarce resource for nodes. Nodes deplete more energy in communication and computation. This energy can be saved by using clustering, in which group of nodes form clusters and Cluster head sends aggregated data to the base station. The selection of cluster head is an important task.