What is meant by Multifactor Authentication (MFA)?

Multifactor Authentication (MFA) is a security mechanism that enhances the verification process of a user's identity by requiring two or more different forms of evidence or factors. These factors typically fall into three categories: something you know (like a password), something you have (such as a smart card or a phone), and something you are (like biometric data). By utilizing multiple forms of authentication, MFA helps to significantly reduce the risk of unauthorized access, as an attacker would need to compromise multiple methods to gain entry.

The other options do not accurately define MFA. Using a single method for user verification refers to single-factor authentication, which is less secure than MFA. Utilizing biometric data can be part of MFA, but it does not encompass the broader concept of requiring multiple forms of verification. Resetting passwords after a set duration is a security practice but does not relate directly to the multifactor aspect of authentication since it doesn't involve the diverse factors needed to confirm identity comprehensively. Therefore, the definition of MFA is best captured by the requirement of multiple forms of evidence to validate a user's identity.