A Frankfurter Würstchen (German for Frankfurt sausage) is a thin parboiled sausage made of pure pork in a casing of sheep's intestine. The special taste is acquired by a special method of low temperature smoking. For consumption, Frankfurters are not cooked; they are only heated in hot water for about eight minutes which prevents the skin from bursting. They are traditionally served with bread, mustard, horseradish and/or potato salad.
Meat sausages as a Frankfurt speciality are already mentioned in medieval sources, often served during the Imperial coronation ceremonies at the Römerberg. Smoked Frankfurter Würstchen have protected geographical status in Germany since about 1860. Since 1929, the indication is only allowed to be used for sausages that are in fact produced in the Frankfurt area, mainly in Neu-Isenburg and Dreieich.
Originally, Frankfurters were made without nitrite curing salt. After the special ageing and smoking methods, the sausages, now of a golden colour, are put into wooden boxes with small parchment paper between layers. Therefore, the traditional sausages are square in shape but there are a few exceptions where the sausage is circular.
Outside Germany, "frankfurter" is a common designation for boiled sausages, such as North American hot dogs, which are called Wiener Würstchen (Vienna sausages) in Germany. In Austria, Vienna sausages are called Frankfurter Würstl as they allegedly were brought to Vienna by Johann Georg Lahner (1772–1845), a butcher trained in Frankfurt, who in 1805 began to produce sausages from a mixture of pork and beef. "Frankfurters" were successful in Austria, North America and other countries, though they differ from the original ones.