Challenge coin

A challenge coin, also known as military coin, unit coin, memorial coin, or commander's coin, is a small coin or medallion, bearing an organization's insignia or emblem and carried by the organization's members. Traditionally, they might be used to prove membership to the issuing organization when asked (the "challenge") or as a commemorative award. They are collected by various people as a form of exonumia. Historically, challenge coins have been presented by unit commanders in recognition of special achievement by a member of the unit, or the unit as a whole. They have also been exchanged in recognition of visits to an organization.

Modern challenge coins are made in a variety of shapes and sizes and often include pop-culture references, including superheroes and other well-known characters.