The purpose of this paper is to explore international university ranking systems. As a compilation study this paper provides specific criteria that each ranking system uses and main critiques regarding these ranking systems. Since there are many ranking systems in this area of research, this study focused on only most cited and referred ranking systems. As there is no consensus in terms of the criteria that these systems use, this paper has no intention of identifying the best ranking system based on a comparative analysis. Rather, this paper may inform relevant interest groups in higher education about the ranking systems and their decisive factors as universities attempt to place their names on the most known ranking systems. This study may provide brief but extensive information to Turkish Higher Education researchers and universities as they participate in Erasmus and Mevlana to open their doors to international higher education world. To become one of the top universities, this paper suggests that universities should know and understand the realities of international competitiveness in higher education and based on such understanding they can mold their physical, structural and academic futures toward achieving their visions and foundational missions.