A hamburger (or burger for short) is a food, typically considered a sandwich, consisting of one or more cooked pattiesusually ground meat, typically beefplaced inside a sliced bread roll or bun. The patty may be pan fried, grilled, smoked or flame broiled. Hamburgers are often served with cheese, lettuce, tomato, onion, pickles, bacon, or chilis, condiments such as ketchup, mustard, mayonnaise, relish, or a 'special sauce', often a variation of Thousand Island dressing, 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 United Kingdom, where the term patty is rarely used, or the term can even refer simply to ground beef. Since the term hamburger usually implies beef, for clarity burger may be prefixed with the type of meat or meat substitute used, as in beef burger, turkey burger, bison burger, portobello burger, or veggie burger. Hamburgers are typically sold at fast-food restaurants, diners, and specialty and high-end restaurants. There are many international and regional variations of hamburgers. Etymology and terminology The term hamburger originally derives from Hamburg, Germany's second-largest city. Hamburger in German is the demonym of Hamburg, similar to frankfurter and wiener, names for other meat-based foods and demonyms of the cities of Frankfurt and Vienna (in German Wien) respectively. By back-formation, the term 'burger' eventually became a self-standing word that is associated with many different types of sandwiches, similar to a (ground meat) hamburger, but made of different meats such as buffalo in the buffalo burger, venison, kangaroo, chicken, turkey, elk, lamb or fish like salmon in the salmon burger, but even with meatless sandwiches as is the case of the veggie burger.