A hamburger (also called a hamburger sandwich, burger or hamburg) is a sandwich consisting of one or more cooked patties of ground meat (beef, pork, turkey, chicken, etc.) usually placed inside a sliced hamburger bun. Hamburgers are often served with lettuce, bacon, tomato, onion, pickles, cheese and condiments such as mustard, mayonnaise, ketchup and relish.
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. The term may be prefixed with the type of meat as in "turkey burger".
The term hamburger originally derives from Hamburg, Germany's second largest city, from which many people emigrated to the United States. In High German, Burg means fortified settlement or fortified refuge and is a widespread component of place names. Hamburger can be a descriptive noun in German, referring to someone from Hamburg (compare London → Londoner) or an adjective describing something from Hamburg. Similarly, frankfurter and wiener, names for other meat-based foods, are also used in Germany and Austria as descriptive nouns for people and as adjectives for things from the cities of Frankfurt and Wien (Vienna), respectively.
The term "burger", a back-formation, is associated with many different types of sandwiches similar to a (ground meat) hamburger, using different meats, such as a buffalo burger, venison, kangaroo, turkey, elk, lamb, salmon burger or veggie burger.
The hamburger, a ground meat patty between two slices of bread, was first created in America in 1900 by Louis Lassen, a Danish immigrant, owner of Louis' Lunch in New Haven, Connecticut. There have been rival claims by Charlie Nagreen, Frank and Charles Menches, Oscar Weber Bilby, and Fletcher David. White Castle traces the origin of the hamburger to Hamburg, Germany with its invention by Otto Kuase. However, it gained national recognition at the 1904 St. Louis World's Fair when the New York Tribune namelessly attributed the hamburger as, "the innovation of a food vendor on the pike." No conclusive claim has ever been made to end the dispute over the inventor of the hamburger with a variety of claims and evidence asserted since its creation.
Hamburgers are usually a feature of fast food restaurants. The hamburgers served in major fast food establishments are usually mass-produced in factories and frozen for delivery to the site. These hamburgers are thin and of uniform thickness, differing from the traditional American hamburger prepared in homes and conventional restaurants, which is thicker and prepared by hand from ground beef. Generally most American hamburgers are round, but some fast-food chains, such as Wendy's, sell square-cut hamburgers. Hamburgers in fast food restaurants are usually grilled on a flat-top, but some firms, such as Burger King, use a gas flame grilling process. At conventional American restaurants, hamburgers may be ordered "rare", but normally are served medium-well or well-done for food safety reasons. Fast food restaurants do not usually offer this option.
The McDonald's fast-food chain sells the Big Mac, one of the world's top selling hamburgers, with an estimated 550 million sold annually in the United States. Other major fast-food chains, including Burger King (also known as Hungry Jack's in Australia), A&W, Culver's, Whataburger, Carl's Jr./Hardee's chain, Wendy's (known for their square patties), Jack in the Box, Cook Out, Harvey's, Shake Shack, In-N-Out Burger, Five Guys, Fatburger, Vera's, Burgerville, Back Yard Burgers, Lick's Homeburger, Roy Rogers, Smashburger, Taco Bell and Sonic also rely heavily on hamburger sales. Fuddruckers and Red Robin are hamburger chains that specialize in the mid-tier "restaurant-style" variety of hamburgers.