A tankard is a form of drinkware consisting of a large, roughly cylindrical, drinking cup with a single handle. Tankards are usually made of silver, pewter, or glass, but can be made of other materials, for example clay or leather. A tankard may have a hinged lid, and tankards featuring glass bottoms are also fairly common. Tankards are shaped and used similarly to beer steins.
Tankards are often found with glass bottoms. The legend is that the glass bottomed tankard was developed as a way of refusing the King's shilling, i.e. conscription into the British army or navy. The drinker could see the coin in the bottom of the glass and refuse the drink, thereby avoiding conscription.
In actuality the glass bottom merely allowed the drinker to judge the clarity of their drink while forgoing the expense of a fragile pint glass.
In previous centuries, the pewter used to make tankards often contained lead, which exposed the drinker to medical effects ranging from heavy metal poisoning to gout. This effect was exacerbated in cider drinking areas such as Somerset, UK, as the acid qualities of the cider leached out the lead content from the pewter more quickly. Clay tankards became prevalent in this area. Pewter is now widely lead-free.