Definition
Multi-Factor Authentication (MFA) is an Authentication mechanism that requires Identity confirmation using at least two independent factors from different categories.
Human Explanation
In addition to a password, a user confirms Identity with another element such as an authenticator application, hardware key or biometric characteristic.
Why it Matters
MFA substantially reduces the Risk of account takeover even when a password is disclosed.
Conceptual Boundary
MFA does not mean using two passwords or two security questions. Factors must belong to different categories, such as knowledge, possession or inherence.
Practical Perspective
MFA is most effective when the additional factor is resistant to interception and difficult to reproduce.