A cheeseburger 's a hamburger accompanied with melted cheese. The term itself's a portmanteau of the words "cheese" and "hamburger." The cheese's usually sliced, then added a short time before the hamburger finishes cooking to allow it to melt. In fast food restaurants, the cheese that's added to a cheeseburger's typically American cheese, but there're many other variations. Mozzarella, blue cheese, pepper jack, and especially cheddar are popular choices. The cheese in a cheeseburger substantia… (More on Cheeseburgers)