Mastercard Inc. (stylized as MasterCard from 1979 to 2016 and as mastercard from 2016 to 2019) 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 (such as travel-related payments and bookings). 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 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.

Although BankAmericard's debut in September 1958 was a disaster, it began to turn a profit by May 1961. Bank of America deliberately kept this information secret and allowed then-widespread negative impressions to linger in order to ward off competition. This strategy was successful until 1966, when BankAmericard's profitability had become far too big to hide. From 1960 to 1966, there were only 10 new credit cards introduced in the United States, but from 1966 to 1968, approximately 440 credit cards were introduced by banks large and small throughout the country. These newcomers promptly banded together into regional bankcard associations.

One reason why most banks chose to join forces was that at the time, 16 states limited the ability of banks to operate through branch locations, while 15 states entirely prohibited branch banking and required unit banking. A unit bank can legally operate only at a single site and is thereby forced to remain very small. By joining a regional bankcard association, a unit bank could quickly add a credit card to its lineup of financial products, and achieve economies of scale by outsourcing tedious back office tasks like card servicing to the association. Such associations also enabled unit banks to aggregate their customer bases and merchant networks in order to make a credit card useful for both customers and merchants; early credit cards had failed because they could only be used within a small radius around their respective issuing banks.

In 1966, Karl H. Hinke, an executive vice president at Marine Midland Bank, asked representatives of several other banks to meet him in Buffalo, New York. Marine Midland had just launched its own regional bankcard in the Upstate New York market after Bank of America declined its request for a BankAmericard regional license on the basis that Marine Midland was too big. The result of the Buffalo meeting was that several banks and regional bankcard associations soon agreed to join forces as Interbankard, Inc., which then became the Interbank Card Association (ICA). By the end of 1967, ICA had 150 members and Hinke became ICA's chairman. Bank of America eventually joined Mastercard as well. (In the 21st century, Bank of America would revive the BankAmericard brand name as a Mastercard credit card, which it remains today).

The Interbank branding in 1966 initially consisted only of a small unobtrusive lowercase i inside a circle in the lower right-hand corner of the front of each Interbank card; the rest of the card design was the prerogative of each issuing bank. This tiny logo proved to be entirely unsatisfactory for creating nationwide brand awareness in order to compete against the established leader, BankAmericard. In 1969, Interbank developed a new national brand, "Master Charge: The Interbank Card" by combining the two overlapping yellow and orange circles of the Western States Bankcard Association with the "Master Charge" name coined by the First National Bank of Louisville, Kentucky.

That same year, First National City Bank joined Interbank and merged its proprietary Everything Card with Master Charge.

In 1968, the ICA and Eurocard started a strategic alliance, which effectively allowed the ICA access to the European market, and for Eurocard to be accepted on the ICA network. The Access card system from the United Kingdom joined the ICA/Eurocard alliance in 1972.