The criteria for identification tend either to be based on a yardstick value (e.g., if the producer-service sector is the largest sector then city X is a world city) or on an imminent determination (if the producer-service sector of city X is greater than the combined producer-service sectors of N other cities then city X is a world city.)Ĭities can also fall from such categorization, as in the case of cities that have become less cosmopolitan and less internationally renowned in the current era. Although there is a consensus upon leading world cities, the criteria upon which a classification is made can affect which other cities are included. Global city status is considered to be beneficial and desired, and because of this, many groups have tried to classify and rank which cities are seen as world cities or non-world cities. More recently, the term has been described as being synonymous with a city's influence and 'financial capital', with other factors becoming less relevant. Patrick Geddes also used the term 'world city' later in 1915. The use of 'global city', as opposed to ' megacity', was popularized by sociologist Saskia Sassen in her 1991 work, The Global City: New York, London, Tokyo although the term 'world city', which refers to cities involved with large amounts of global business, dates to at least the May 1886 description of Liverpool, by The Illustrated London News. The most complex of these entities is the 'global city', whereby the linkages binding a city have a direct and tangible effect on global affairs through socio-economic means.

The concept comes from geography and urban studies, and the idea that globalization can be understood as largely created, facilitated, and enacted in strategic geographic locales according to a hierarchy of importance to the operation of the global system of finance and trade.

A global city, also called world city or sometimes alpha city or world center, is a city generally considered to be an important node in the global economic system.

Alpha-global city