Authentication
Formal
In computing, authentication is the process of verifying the identity of a person or device, preventing unauthorized access and misuse of personal information.
Practical
Authentication is the act of confirming the truth of an attribute of a single piece of data (a datum) claimed true by an entity. In contrast with identification which refers to the act of stating or otherwise indicating a claim purportedly attesting to a person or thing's identity, authentication is the process of actually confirming that identity.