thumb|right|upright=1.3|[[Stoneware beer steins]]
A beer stein ( ), or simply stein, is either a traditional beer mug made out of stoneware or specifically an ornamental beer mug sold as a souvenir or collectible.
Such steins may be made out of stoneware, pewter, porcelain or even silver, wood or crystal glass; they may have open tops or hinged pewter lids with a thumb-lever. Steins usually come in sizes of a half litre, a full litre, or historically the similarly sized pints and quarts from which the saying "mind your P's and Q's" is derived. Like decorative tankards, they are often decorated in a nostalgic manner with allusions to Germany.
Etymology
thumb|upright|A typical half-litre German [[:de:Humpen|Humpen (beer mug)]]
The English word is attested from 1855. It is borrowed from German ', which has – aside from its prevailing meaning "stone" – elder regional meanings "beer mug" and "beer measure of 1 litre or 2 Schoppen".
The word can be compared to English stean "stone or earthen vessel", and Old English "pitcher, jug".
The word ' alone is not used any more to refer to a beverage container in standard German; rather, ', ' or, especially in Bavaria and Austria, ' are used. Oktoberfest usage is Maßkrug.
History
It is believed by some that the hinged lid was implemented during the age of the Black Plague to prevent diseased flies from getting into the beer.
This is unlikely to be true, as contemporaries did not know flies spread the disease. Instead, the prevailing belief was that it was spread through dangerous "miasmas".
The advantage in using stoneware to make steins was that molds could be used to mass-produce elaborately carved steins. On the other hand, glass had the advantage that one could add an artistic touch by including acid etchings, glass staining, or even multicolored overlays. Porcelain's advantage was that a stein fabricator could use molds to make "character steins", steins that had a particular shape modeled after an item or a person. In the 20th century, collecting antique and replicated beer steins became a popular hobby not only among individual people, but in museums as well. Production of beer steins has become substantial in America, but the largest producer of beer steins is Ceramarte of Brazil. Steins have also been known to have been made out of wood, earthenware, and crystal. to replace beer mugs made from glass or earthenware by ones made from plastic (for security reasons) have been variously met with protests, even burnings of mugs and were never successful in the long or even medium term in Germany.
The lid
The lids on beer mugs serve as a sanitary measure, especially to keep insects out of the beer.