Abstract: Wireless Sensor Network is the combination of small sensor nodes which sense the data from its surroundings such as temperature etc. then the collected or sensed data travels from source node to sink node via a selected and efficient route. The process of data transmission accomplishes by consuming the amount of energy. The energy consumption directly affects the lifetime of the network. Hence the performance and lifetime of the network is depends upon the amount of energy consumed by the nodes. There are various protocols which are used for reducing the energy consumption of the nodes by various means such as selection or route to the sink node and section of cluster heads. So this paper provides a review to the various techniques used for selecting the cluster heads for the network. The cluster head selection is a crucial part of the network. Because the node selected as cluster head is responsible for data transmission between sources and sink node. So the candidate node for cluster head should have required amount of energy so that it can remain live for long period and enhances the performance and lifetime of the network.

Keywords: WSN, Low Energy Adaptive Clustering Hierarchy, Routing, Cluster heads, TEEN.