The Diners Club was the company that introduced what can be called the world's first "general purpose" credit card. It was basically a charge card, which was like a credit card, but the entire payment had to be made with each statement. The Diners Club was formed in the United States partially through a merger with the companies Dine and Sign. 20,000 such cards were used throughout the country within a year. American Express as well as Carte Blanche credit cards were introduced shortly after.
The story goes that Frank McNamara had to call his wife as he had forgotten his wallet while dining in New York City at Major's Cabin Grill. He was determined never to face that kind of humiliation again. Thus the Diners Club credit card was born.