How cryptocurrency scams work

Millions of cryptocurrency investors have been scammed out of massive sums of real money. In 2018, losses from cryptocurrency-related crimes amounted to US$1.7 billion. The criminals use both old-fashioned and new-technology ...

Can flipping coins replace animal experiments?

Instead of repeating an experiment in a mouse model of disease in their laboratory, researchers in Berlin, Germany used a coin toss to confirm whether a drug protects the brain against a stroke, as reported in their paper ...

JPMorgan Chase unveils cryptocurrency prototype

JPMorgan Chase on Thursday unveiled a prototype for a digital coin system using blockchain, a first among major banks as disruption accelerates change in financial services.

Facial recognition for coins

Countless historical coins that differ from each other only in details are in storage at German state museums. Unlike paintings, these archaeological artifacts may not be labeled, marked or barcoded. Researchers at the Fraunhofer ...

How two metal detectorists discovered a complete Roman treasure

In 2017, in an ordinary field, two brothers from Brabant discovered more than 100 ancient coins. The Leiden historian who examined the coins concluded that they constituted a genuine Roman treasure. Here follows a reconstruction ...

900-year-old gold coins found in Israel

Rare gold coins and a golden earring have been discovered in the ancient Mediterranean port of Caesarea in northern Israel—possibly left and never recovered as Crusaders conquered the area 900 years ago.

Cryptocurrencies: High volatility and returns

It's been an extremely volatile year for Bitcoin prices. About a year ago, Bitcoin was trading in a range of $4,000 to $5,000. After climbing to a high of just over $20,000 in December 2017, it now seems to be back where ...

Parrondo's paradox with a three-sided coin

Physicists have demonstrated that Parrondo's paradox—an apparent paradox in which two losing strategies combine to make a winning strategy—can emerge as a coin game with a single coin in the quantum realm, but only when ...

New NIST research could bring down the cost of making nickels

Nickels are ubiquitous in American life, tumbling around in pockets, rolling under car seats, and emerging from the back of dryers to be used over and over for countless purchases. But these resilient and somewhat humble-looking ...

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A coin is a piece of hard material that is standardized in weight, is produced in large quantities in order to facilitate trade, and primarily can be used as a legal tender token for commerce in the designated country, region, or territory.

Coins are usually metal or a metallic material and sometimes made of synthetic materials, usually in the shape of a disc, and most often issued by a government. Coins are used as a form of money in transactions of various kinds, from the everyday circulation coins to the storage of large numbers of bullion coins. In the present day, coins and banknotes make up currency, the cash forms of all modern money systems. Coins made for paying bills and general monetized use are usually used for lower-valued units, and banknotes for the higher values; also, in many money systems, the highest value coin made for circulation is worth less than the lowest-value note. In the last hundred years, the face value of circulation coins has usually been higher than the gross value of the metal used in making them; exceptions occurring when inflation causes the metal value to surpass the face value, causing the minting authority to change the composition and the old coins to begin to disappear from circulation (see Gresham's Law.) However, this has generally not been the case throughout the rest of history for circulation coins made of precious metals.

Exceptions to the rule of coin face-value being higher than content value, also occur for some bullion coins made of silver or gold (and, rarely, other metals, such as platinum or palladium), intended for collectors or investors in precious metals. Examples of modern gold collector/investor coins include the American Gold Eagle minted by the United States, the Canadian Gold Maple Leaf minted by Canada, and the Krugerrand, minted by South Africa. The American Gold Eagle has a face value of US$50, and the Canadian Gold Maple Leaf coins also have nominal (purely symbolic) face values (e.g., C$50 for 1 oz.); but the Krugerrand does not.

Historically, a great number of coinage metals (including alloys) and other materials have been used practically, artistically, and experimentally in the production of coins for circulation, collection, and metal investment, where bullion coins often serve as more convenient stores of assured metal quantity and purity than other bullion.

Coins have long been linked to the concept of money, as reflected by the fact that in some other languages the words "coin" and "currency" are synonymous. Fictional currencies may also bear the name coin (as such, an item may be said to be worth 123 coin or 123 coins).

This text uses material from Wikipedia, licensed under CC BY-SA