A challenge coin is a small coin or medallion, bearing an organization's insignia or emblem and carried by the organization's members. Challenge coins have been used as a valuable recognition tool dating back to the First World War. Military units began using challenge coins as a discreet way of claiming membership to a specific unit. The possession of a challenge coins was known to have saved the life of a captured American service man during a rescue attempt. The coin was the only form of identification in his possession that proved he was a member of the American military forces. An individual possessing challenge coins would be proud to know that he or she is a member of a group that shares commitment, loyalty and dedication to a common goal.