What is challenge coin ？

What is challenge coin ？like the story of the most important thing is that the floating, (there are quite a few and has not been proved to be accurate account started to challenge COINS) can be traced back to world war ii OSS (strategic service office) deployed to the Nazi held in France.COINS COINS only local, in the process of meeting as a sincerity to verify the truthfulness of the identity and OSS agent.

What is challenge coin ？like the story of the most important thing is that the floating, (there are quite a few and has not been proved to be accurate account started to challenge
Details on the coin is by each party to check identification friend-or-foe, prevent infiltration agents may know the time of the meeting in advance, location, or even a coin.This helps prevent spies to infiltrate the meeting, they may need to know in advance the meeting time, place, or even a coin.
The first military units a coin is the oldest known special forces troops, 10 special forces team.Green beret units have a coin is the only known created before the U.S. special operations command (USSOCOM) in 1987.Since then, challenges the traditional coin has spread far and wide in the military and the private sector.
May not have a President or government officials, no one today.I think the coolest COINS to me I collect the admiral was chosen to honor the recruitment in boot camp, give me another Texas governor Rick Perry (Rick Perry) shows a few years ago.