Mastercard Inc. (stylized as MasterCard from 1979–2016, mastercard from 2016–2019) is the second-largest payment-processing corporation worldwide. It offers a range of financial services. Its headquarters are in Purchase, New York. Throughout the world, its principal business is to process payments between the banks of merchants and the card-issuing banks or credit unions of the purchasers who use the Mastercard-brand debit, credit and prepaid cards to make purchases. Mastercard has been publicly traded since 2006.

Mastercard (originally Interbank then Master Charge) was created by an alliance of several banks and regional bankcard associations in response to the BankAmericard issued by Bank of America, which later became Visa, still its biggest competitor. Prior to its initial public offering, Mastercard Worldwide was a cooperative owned by the more than 25,000 financial institutions that issue its branded cards.