Challenge coin is a small coin or medallion, which depicts the signs of the organization, various emblems. Traditionally, such coins exist to prove belonging to some society, and to improve the morale of the owner. Such coins are also collected by the military and law enforcement officers. For 2019, complex coins come in different sizes, refer to popular cultures, sometimes creating even a semblance of a parody. Historically, such challenge coins were in the unit commanders as a sign of certain achievements. The exchange of such coins can be regarded as a sign of recognition during visits to the organization.

 Historically, the challenge coin appeared during the First world war, and saved on the facts of a few lives when the soldiers were not documents, but there was a need to confirm their affiliation to the different types of troops. According to another theory, such coins prevented the appearance of spies, being a kind of identification mark. The coin challenge were popular during the Vietnam war, and in some units the tradition persisted until the 1980s.

 Coins issued in small quantities had political significance, such coins were issued almost by the communications Agency of the White house. Special coins for heads of foreign States and military were issued. This tradition dates back to the late 1990s and continues to this day. All the Presidents of the United States had such special coins.

 The tradition of challenge coins is the most common way to ensure that the participants carried the coins of their unit. Call rules can vary between organizations. In the competition have the right to attend only those members of the community, who formally was the date of this coin.

 The test can be performed at any time, and begins with the fact that the applicant pulls out a coin and puts the coin on the table. With enough noise in the establishment, continuous tapping of the challenge coin on the surface can initiate the challenge. Each in which the participants have doubt, must produce the coin for their organization, and those who do not, must buy a round of drinks for the Challenger and for everyone who has a challenge coin. Based on this, most of those who have a coin challenge carry it in an easily accessible place to be able to answer the challenge. The grade of a coin is determined by the ranks, if it is a military coin. The higher the position, the higher the coin price.

 In addition to the military, coin testers are popular among motorcycle owners club Harley-Davidson. Wearing the Harley-Davidson coin is a very significant way to show pride in owning Harley-Davidson, as well as pay tribute to those who serve in the army.

 Apart from the United States of America the coin challenge is practiced in Canada, Switzerland, Australia, New Zealand and the UK.

 This feature and tradition, which has the challenge of the coin, is extremely interesting, and it is a pity that it is observed in a very narrow range of countries and organizations.