In order to be successful in competition, businesses seek long-term ways that cannot be easily imitated by competitors.  Even though traditional sources of success or competitive advantages are still competitively important, they no longer have their former strength since they are easily imitated by competitors. Instead, people and how they will be managed have become more important. Human resource, which is one of the most important resources of the organization, also gains importance. Recently, one of the most important issues of both the existence of qualified employees and the organizations is to ensure that the behavior of their employees is based on volunteerism beyond necessity. This situation has led to the prominence of organizational citizenship behavior in the organizational behavior literature in recent years. It started in the 1930s and has been studied in different ways and has survived to the present day. In order for a behavior within the organization to be qualified as organizational citizenship behavior, it is expected that it should be voluntary, be beyond the job description, and not be formally rewarded. In Organ (1988), altruism, courtesy, civic virtue, conscientiousness and sportsmanship were the dimensions. There are various theories developed in the literature that explain how organizational citizenship behavior emerges under the influence of which factors in individuals. These are social exchange, equality, expectation, leader member exchange, and reciprocity norm theory. The factors affecting organizational citizenship behavior are considered as organizational commitment, job satisfaction, justice, identification, leader, person and organization characteristics. Finally, individual and organizational consequences caused by organizational citizenship behavior are discussed and given in the last section.