https://corpgov.law.harvard.edu/2017/03/25/ne...to-effect/
Quote:(f) Multi-Factor Authentication means authentication through verification of at least two of the following types of authentication factors:
(1) Knowledge factors, such as a password; or
(2) Possession factors, such as a token or text message on a mobile phone; or
(3) Inherence factors, such as a biometric characteristic.