A German beer stein is a beverage container complete with a hinged lid and handle that is designed specifically for drinking beer. They are usually characterized as being larger and sturdier than traditional pint glasses, mugs or other forms of drinkware.
The word "stein" itself is German, and comes as a shortened, colloquial form of the word "Steinzeugkrug," which is a stoneware jug or tankard. In modern usage, stein refers to most any beer container, but a traditional German beer stein would most likely be identified by both a long handle and a hinged lid, in addition to a thicker material construction than many other drinking containers.
The important distinction to be made between a classic mug and a German beer stein is the hinged lid, which was first created as a sanitary measure to protect German drinkers from insects and disease during the bubonic plague. Traditionally, the hinged lid is operated by a simple lever known as a thumblift, which allows drinkers to hold the stein and open and close the lid with one hand.
From a material standpoint, German beer steins can be crafted from any number of substances, though the most popular are wood, stone, glass and metal, particularly silver.