In this paper, the authors have discussed about the Wireless Sensor Networks (WSN). Wireless Sensor Network (WSN) consists of collection of tiny device called sensors nodes. Sensor node has a resource constraint (i.e. battery power, storage and communication capability). These sensor nodes are set with radio interface by which they are communicated with one to another to lead to the formation of a network. The ongoing improvement in sensor technology is the reason for the rapid popularity of the WSN and thus it has wide and varied application.