The concept originates from geography and urban studies, based on the thesis that globalization has created a hierarchy of strategic geographic locations with varying degrees of influence over finance, trade, and culture worldwide.[5] Common features include a high degree of urban development, a large population, the presence of major multinational companies, a significant and globalized financial sector, a well-developed and internationally linked transportation infrastructure, local or national economic dominance, high quality educational and research institutions, and a globally influential output of ideas, innovations, or cultural products.[20] Together with Jon Beaverstock and Richard G. Smith, they create the GaWC's biennial categorization of world cities into "Alpha", "Beta" and "Gamma" tiers, based upon their international connectedness.[21] Primarily concerned with what is calls the "advanced producer services" of accountancy, advertising, banking/finance, and law, the cities in the top two classifications in the 2024 edition are:[22] In 2008, the American journal Foreign Policy, working with the consulting firm A.T. Kearney and the Chicago Council on Global Affairs, published a ranking of global cities based on consultation with Saskia Sassen, Witold Rybczynski, and others.[23][24] The ranking is based on 27 metrics across five dimensions: business activity, human capital, information exchange, cultural experience, and political engagement.