A hamburger, beefburger or burger is a sandwich consisting of one or more cooked patties of ground meat, usually beef, placed inside a sliced bread roll or bun. The patty may be pan fried, barbecued, or flame broiled. Hamburgers are often served with cheese, lettuce, tomato, bacon, onion, pickles, or chiles; condiments such as mustard, mayonnaise, ketchup, relish, or "special sauce"; and are frequently placed on sesame seed buns. A hamburger topped with cheese is called a cheeseburger.
The term "burger" can also be applied to the meat patty on its own, especially in the UK where the term " patty " is rarely used, or the term can even refer simply to ground beef. The term may be prefixed with the type of meat or meat substitute used, as in " turkey burger", " bisonburger", or " veggie burger ".
Hamburgers are sold at fast- food restaurants, diners, and specialty and high-end restaurants (where burgers may sell for several times the cost of a fast- food burger, but may be one of the cheaper options on the menu). There are many international and regional variations of the hamburger.