Big Mac was the trademarked name of McDonald's sandwich introduced nationally in 1968.
The sandwich was created by franchisee Jim Delligatti, who operated McDonald's restaurants in the Pittsburgh area. It used two beef patties, a middle bun section, lettuce, cheese, pickles, onions, and the sauce that became closely associated with the product.
Delligatti first tested the sandwich locally before McDonald's rolled it out across the United States. Its distinctive name helped turn the product into a major part of the company's brand identity rather than merely another menu item.
The Big Mac is often confused with the Quarter Pounder, which is a different sandwich built around a larger single beef patty. The Big Mac's defining visual and structural feature is its three-part sesame-seed bun and two-patty arrangement.