McDonald's signature double-decker hamburger introduced in 1967 was the Big Mac.
The sandwich was created by Jim Delligatti, a McDonald's franchisee in the Pittsburgh area. It used two beef patties, a middle bun section, lettuce, cheese, pickles, onions, and the sauce now associated with the product. McDonald's introduced it nationally in 1968 after regional testing.
The Big Mac became more than a menu item: its name, packaging, layered construction, and advertising made it a durable part of McDonald's product branding. It is sometimes confused with the Quarter Pounder, which is identified by the weight of its beef patty rather than by a three-part bun.
The Big Mac's later international fame also led economists to use its price in the informal Big Mac Index for comparing currencies.