Opinion leaders are defined as people who are seen as reliable by the individuals around them, who influence the individuals they interact with the feelings and thoughts they share and who have the potential to direct them. With new communication technologies, especially social media, opinion leadership in the traditional sense has moved to a different dimension and online opinion leaders have emerged. In addition, it can be seen that offline opinion seeking activity, which can be carried out through opinion leaders and various sources has become more possible in online areas. On the other hand, the concept of echo chamber, which refers to the exposure of individuals to similar thoughts and beliefs in online spaces as a reflection of selective exposure has started to be discussed. Which individuals are exposed to echo chambers and which individuals exhibit avoidance behavior from echo chambers are among the questions to be answered in the field. In this context, the book examines whether individuals are exposed to echo chambers by categorizing them as offline and online opinion leaders, offline and online opinion seekers.