The Globalization and World Cities Research Network, commonly abbreviated to GaWC, is a think tank based in the Geography department at Loughborough University in England, that studies the relationships between world cities in the context of globalization.
GaWC was founded by Peter J. Taylor in 1998, Together with Jon Beaverstock and Richard G. Smith, they create the GaWC's bi-annual categorization of world cities into "Alpha", "Beta" and "Gamma" tiers, based upon their international connectedness.
The GaWC examines cities worldwide to narrow them down to a roster of 307 world cities, then ranks these based on their connectivity through four "advanced producer services": accountancy, advertising, banking/finance, and law. The GaWC inventory ranks city economics more heavily than political or cultural factors. Beyond the categories of "Alpha" world cities (with four sub-categories), "Beta" world cities (three sub-categories) and "Gamma" world cities (three sub-categories), the GaWC cities include additional cities at "High sufficiency" and "Sufficiency" level.
The following is a general guide to the rankings as of the most recent (2012) update:
Alpha++ cities are vastly more integrated with the global economy than all other cities.
Alpha+ cities are the eight cities that complement London and New York City by filling advanced service niches for the global economy.
Alpha and Alpha- cities are the 13 and 22 cities, respectively, that link major economic regions into the world economy.
The GaWC global cities according to the 2012 study:
Beta level cities are the 78 cities that link moderate economic regions into the world economy.
Gamma level cities are the 59 cities that link smaller economic regions into the world economy.
High Sufficiency level cities are the 41 cities that have a high degree of accountancy, advertising, banking/finance, and law services so as not to be dependent on world cities.
Sufficiency level cities are the 84 cities that have a sufficient degree of services so as not to be obviously dependent on world cities.