The Big Mac became McDonald's signature sandwich when it was 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 chain’s special sauce.
Its distinctive three-part bun and layered construction gave McDonald's a highly recognizable product identity. The Big Mac later became one of the company’s most internationally known menu items and a recurring centerpiece of its advertising.
The Big Mac is sometimes confused with the Quarter Pounder because both are major McDonald's hamburgers. The Quarter Pounder is defined by its beef-patty weight before cooking, while the Big Mac is defined by its layered recipe.