A hamburger is typically considered to be a variant on a sandwich involving a patty of ground beef. The name comes from the German city of Hamburg, something from Hamburg being "hamburger"; such ground beef patties originating or enjoying early popularity there. Originally these patties were known as "Hamburger steak", and when this was put between bread or in a bun it was called a "Hamburger sandwich". By the mid 20th century both terms were commonly shortened to "hamburger" or simply "burger".
There are two independent definitions of what differentiates a burger from a sandwich:
- Burgers use processed meat, regardless of the type of bread.
- Burgers use a "burger" bun, regardless of the filling.
Ingredients for a burger vary.
- In American restaurants, burgers are traditionally offered "with everything" (or "all the way," or in some regions "dressed") -- which includes lettuce, tomato, onion, and often a pickle (or pickle relish) -- or "hold the onions" -- with lettuce and tomato and maybe pickle; cheese (usually American processed cheese, but often cheddar, Swiss, or bleu, either melted on the meat patty or crumbled on top) is generally an option and technically makes it a "cheeseburger" instead of a "hamburger." Condiments are usually offered separately (= "on the side"), most commonly mustard and ketchup, although mayonnaise and other salad dressings are popular, as are salsa and other kinds of peppers. Some restaurants offer hamburgers with bacon and guacamole, as well.
- Australian hamburgers generally include tomato, lettuce, cheese, and meat (with BBQ or tomato sauce) as minimum, and can be optioned to include beetroot, onion, egg, bacon, and pineapple (aka "burger with the lot").