Wireless Sensor Networks (WSNs) are being used in many applications such as: health care monitoring, environmental/Earth sensing, industrial monitoring, data logging. But in order to make use of their potential, researchers must find solution to some difficulties that are slowing down the wide spread use of these networks. These difficulties are inherent to their constrained specificities which require adapted solutions unrelated to classical wire networks. The number of packets sent/received by WSN has a huge impact on the amount of energy consumed. In order to reduce this number (indirectly reduce energy consumption) and to ensure at the same time WSN successful operation, hierarchical clustering protocols have been developed.