Demographic changes of last decades about the city made it necessary to handle this subject in terms of world-city system. Since 2000, almost more than the half of world’s population have been living in the cities. The cities should be taken into consideration as a whole together with all cities of the world. As most of the world’s population live in the cities and the human being share similar organizations in these cities, similar production and consumption processes, similar types of international pollutions, similar transfrontier fight against the environmental pollution all necessitates a “world city-system” for the issues of the city. There are about 200 cities on the world today. Among them, there are various relations especially in politic, economical and social life spaces. According to these relations, it is accepted that there is an international system on the world. Today, there are about 500 cities contains at least 1 million people on the world. The majority of them also have similar relations between themselves. According to this transformation, it is possible to talk about a “World City-System”. Thus, the subject has been studying since 1990’s, under various titles. In this approach, the cities which share similar economic, informatics, and cultural characteristics are examined within an interactive “system”. Some of the authors of related articles and books of limited number of experts and academics are; Peter J. Taylor, G. Catalano, D. R. F. Walker, David A. Smith, Michael Timberlake, Jeffrey Kentor, Roberto Capello.
City, Urbanization, World City-System.