Definition of "authentication" []

• Something which validates or confirms the authenticity of something (noun)
• Proof of the identity of a user logging on to some network (noun)
• A hallmark or assay-mark on a piece of metalwork (noun)

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• "PCGS is the world's largest rare coin authentication company and a division of Collectors Universe, Inc."
• "In addition, there are reliable rare coin authentication companies whose certified coins are guaranteed for authenticity."
• "Re-authentication is required if the game is re-installed on a previously authorized machine for any reason."