In numismatics, token coins or trade tokens are coin-like objects used instead of coins. The field of token coins is part of exonumia and token coins are token money. Their denomination is shown or implied by size, color or shape. They are often made of cheaper metals like copper, pewter, aluminium, brass and tin, or non-metals like bakelite, leather and porcelain. A legal tender coin is issued by a governmental authority and is freely exchangeable for goods. A token coin is less useful and issued by a private entity. Trade or barter Coin-like objects from the Roman Empire called have been interpreted as an early form of token. Their functions are not documented, but they appear to have been brothel tokens or possibly gaming tokens. Medieval English monasteries issued tokens to pay for services from outsiders. These tokens circulated in nearby villages, where they were called "Abbot's money". Also, counters called jetons were used as small change without official blessing. From the 17th to the early 19th century in the British Isles (and also elsewhere in the British Empire) and North America, tokens were commonly issued by merchants in times of acute shortage of coins of the state. These tokens were in effect a pledge redeemable in goods, but not necessarily for currency. These tokens never received official sanction from government but were accepted and circulated quite widely. In England, the production of copper farthings was permitted by royal licence in the first few decades of the 17th century, but production ceased during the English Civil War and a great shortage of small change resulted. This shortage was felt more keenly because of the rapid growth of trade in the towns and cities, and this in turn prompted both local authorities and merchants to issue tokens. These tokens were most commonly made of copper or brass, but pewter, lead and occasionally leather tokens are also found. Most were not given a specific denomination and were intended to substitute for farthings, but there are also a large number of halfpenny and sometimes penny tokens. Halfpenny and penny tokens usually, but not always, bear the denomination on their face. Most such tokens show the issuer's full name or initials. Where initials were shown, it was common practice to show three initials: the first names of husband and wife and their surname. Tokens would also normally indicate the merchant establishment, either by name