Authentication (from Greek: αὐθεντικόςauthentikos, "real, genuine", from αὐθέντης authentes, "author") is the act of proving an assertion, such as the identity of a computer system user. In contrast with identification, the act of indicating a person or thing's identity, authentication is the process of verifying that identity.[1][2] It might involve validating personal identity documents, verifying the authenticity of a website with a digital certificate,[3] determining the age of an artifact by carbon dating, or ensuring that a product or document is not counterfeit.