What does multi-factor authentication often include as one form of verification?

Multi-factor authentication (MFA) is a security mechanism that requires users to provide two or more forms of verification when accessing a system. This increases security by combining multiple authentication methods, making it more difficult for unauthorized users to gain access.

Biometric identifiers, such as fingerprints, facial recognition, or iris scans, represent one of the most secure forms of verification included in multi-factor authentication. These methods rely on unique physical characteristics of the user, adding an additional layer of security beyond something the user knows (like a password) or has (like a security token).

In contrast, security questions can often be easily guessed or researched, making them less reliable. Relying solely on a username and password does not meet the definition of multi-factor authentication, as it only uses a single factor. Server-side data logging pertains more to tracking user activity and is not a direct method of user verification. Therefore, biometric identifiers are a fitting choice when discussing the various components that make up multi-factor authentication methods.