The Big Mac was introduced by McDonald's in 1968 and became a major brand symbol.
The sandwich was created by Jim Delligatti, a McDonald's franchisee who operated restaurants in the Pittsburgh area. It used two beef patties, a middle bun section, lettuce, cheese, pickles, onions, and the sauce later strongly associated with the product. The layered construction made it visually distinctive within the McDonald's menu.
The product's name became part of McDonald's wider branding because it was short, memorable, and easy to recognize internationally. Its advertising also helped establish the ingredient-focused chant that many customers associate with the sandwich.
The Big Mac is sometimes confused with the Quarter Pounder, which is a different McDonald's hamburger introduced earlier. The Big Mac's defining feature is its two-patty, three-part bun structure, not the weight implied by the Quarter Pounder name.