The form and extent of a city's integration into the world economy is vital for understanding structural change occuring within it. Key cities are used as 'basing points' for global capital. These linkages allow world cities to be arranged in a spatial hierarchy. The global control functions of world cities are directly reflected in the form and extent of their production sectors and employment. World cities are major sites for the concentration and accumulation of capital.
World cities are the destination of large numbers of migrants.
World city formation brings into focus major disparities of global capitalism - among them spatial and class polarisation. World city growth produces social costs at rates above and beyond the state's fiscal ability to respond. Friedmann argues that the new international division of labour is organised through a class of cities designated world cities. Global cities have become complex nodes of production and services with internal networks. The production and services activities within cities are governed by entities, both public and private, that are in turn governed by, or part of, larger global strategies.