Wireless Sensor Network (WSN) is a self-organized network composed by a large number of micro-sensors that are randomly deployed in monitoring regional through wireless communication. In Wireless Sensor Networks (WSNs), due to the limitation of nodes' energy, energy efficiency is an important factor should be considered when the protocols are designing. So designing efficient routing for reducing energy consumption is the important factor. This paper also reviews the most energy efficient protocol named LEACH along with its advantages and disadvantages. Finally this paper concludes with some comparison of descendants of LEACH with LEACH protocol.