Quick Answer: Mastercard Inc. is an American multinational payment card services corporation headquartered in Purchase, New York. It offers a range of payment transaction processing and other related-payment services. 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 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 and is still its biggest competitor. Along with Visa, Mastercard has faced numerous antitrust lawsuits. 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.