A card association is a network of issuing banks and acquiring banks that process payment cards of a specific brand.
Familiar payment card association brands include Visa, MasterCard, American Express, Discover, Diner's Club, and JCB. Visa, MasterCard and American Express issuers co-brand with their card association. for example, "WellsFargo-Visa" and "Citi-MasterCard".
Card associations Visa and MasterCard each comprise over 20,000 card issuing banks [1].
Among US consumers alone, over 600,000,000 payment cards are in circulation [2].
Worldwide, Visa issuers have over 1.5 billion payment cards in circulation[3] [4].