A cheeseburger is a hamburger with cheese added to it. Traditionally the cheese is placed on top of the patty, but the sandwich can include many variations in structure, ingredients, and composition. The term itself is a portmanteauof the words “cheese” and “hamburger.” The cheese is usually sliced, then added shortly before the hamburger finishes cooking to allow it to melt. Cheeseburgers are often served with lettuce, tomato, onion, pickles, mustard, mayonnaise, gherkins or ketchup. In fast food restaurants, the cheese is typically processed cheese, but there are variations, such as Cheddar, Swiss, Mozzarella, Blue cheese, and Pepper jack.

The cheese in a cheeseburger can substantially change its nutritional value. For example, a slice of Cheddar can add 95 calories and 4.5 grams of saturated fat to a burger. Other types and amounts of cheese would have varying effects, depending on their nutritional content.

Adding cheese to hamburgers became popular in the mid-1920s to mid-1930s and there are several competing claims as to who created the first cheeseburger. Lionel Sternberger is reputed to have invented the cheeseburger at the age of 16 when he was working as a fry cook at his father’s Pasadena, California sandwich shop, and “experimentally dropped a slab of American cheese on a sizzling hamburger.”

Other restaurants say they invented the cheeseburger, such as Kaelin’s Restaurant in Louisville, Kentucky, who say they invented the cheeseburger in 1934. One year later, a trademark for the name “cheeseburger” was awarded to Louis Ballast of the Humpty Dumpty Drive-In in Denver, Colorado.