A cheeseburger is a hamburger with cheese on top of the patty. The term itself is a portmanteau of the words "cheese" and "hamburger." The cheese is usually sliced, then added a short time before the hamburger finishes cooking to allow it to melt. Cheeseburgers are often served with lettuce, tomato, onion, pickles, and condiments such as mustard, mayonnaise, and ketchup. In fast food restaurants, the cheese that's added to a cheeseburger is typically American cheese, but there are many other va… (More on Cheeseburgers)