A cheeseburger is a hamburger topped with cheese. Traditionally, the slice of cheese is placed on top of the meat patty, but the burger can include many variations in structure, ingredients, and composition. The cheese is normally added to the cooking hamburger patty shortly before the patty is entirely cooked, which allows the cheese to
melt. As with other hamburgers, a cheeseburger may include toppings, such as
lettuce, tomato, onion, pickles, mustard, mayonnaise, ketchup, or
bacon.