National Cheeseburger Day is celebrated on September 18, 2019. 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 term itself is a portmanteau of the words "cheese" and "hamburger." The cheese is usually added to the cooking hamburger patty shortly before the patty is completely cooked which allows the cheese to melt. Cheeseburgers are often served with lettuce, tomato, onion, pickles, mustard, mayonnaise, or ketchup.
In fast food restaurants, the cheese used is typically processed cheese, but there are variations, such as cheddar, Swiss cheese, mozzarella, blue cheese and pepper jack. When cheese is added to a burger the nutritional value of the burger can be changed substantially. For example, a slice of Cheddar cheese can add 113 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. (With material from: Wikipedia)