The McDonald's Corporation is the world's largest chain of hamburger fast food restaurants. Headquartered in the United States, the company began in 1940 as a barbecue restaurant operated by Richard and Maurice McDonald. In 1948, they reorganized their business as a hamburger stand using production line principles. Businessman Ray Kroc joined the company as a franchise agent in 1955. He subsequently purchased the chain from the McDonald brothers and oversaw its worldwide growth.