Social media marketing refers to a set of marketing activities that leverage social relationships among consumers to increase sales. There are different types of marketing using social media like word of mouth marketing, innovation diffusion, buzz marketing and viral marketing [1]. Among these network marketing examples, word of mouth marketing is more credible [2], because there is no direct connection between the sender and the merchant. Accordingly, the information is considered independent and subjective. In recent years, much research in word-of-mouth marketing has focused on discovering influential nodes in a social network. These influential people are called opinion leaders in the literature. Organizations interested in e-commerce need to identify the thought leaders among their customers, as well as where (website) they connect. This is the place where they can market their product.1.1. Social Network Analysis When it comes to the importance of interpersonal relationships, studies seek a formal method to measure "who talks to whom" in a community. These methods are known as social network analysis [3, 4, 5, 6]. Social network analysis includes the study of interpersonal relationships. It is generally more focused on the network itself than on the attributes of its members [2]. Valente and Rogers [7], described social network analysis from the perspective of interpersonal communication by “using formal methods to measure who speaks to whom within a community”. Social network analysis allows researchers to identify people who are more central in the network and therefore more influential. By using these central people or opinion leaders as seeds for disseminating ...... middle of paper ...... leadership and using social media to improve the marketing response, it is possible. In section 2, the concept of opinion leadership as well as the different titles (opinion leaders, influential people, market players and key players) which have been introduced by different studies to designate the influential group in social networks are discussed. Then, regarding the similarity of these titles on the concept and common identifying factors, considering all the proposed definitions and characteristics for thought leaders, influencers, market mavens and key players, three overall classifications including structural, relational and personal characteristics are proposed. In the third section, the methods for identifying and selecting opinion leaders are examined and the appropriate parameters for analyzing these methods are extracted and presented in a comprehensive diagram..