How does a "credential" differ from an "identifier" in access control?

In access control systems, a "credential" generally refers to an object or a set of information that is provided for authentication purposes, allowing an individual to gain access to a system, facility, or resource. This can include physical items such as ID cards, smart cards, or tokens. An "identifier," on the other hand, is typically a piece of information that distinguishes one user from another, such as a username or ID number.

The correct distinction made in this choice highlights that credentials can manifest in tangible or physical forms, while identifiers usually exist in a digital or less tangible format. For example, a user might present a badge or card as a credential at a secure entry point, while their username would serve as their identifier in an online system.

The other options rest on inaccurate definitions or associations between credentials and identifiers, which do not align with the standard meanings in access control terminology. Understanding these differences is crucial for designing effective access control mechanisms that ensure secure authentication while accurately identifying individuals.