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.