Multi-factor Authentication (MFA) is an authentication method that requires the user to provide two (2SV) or more (MFA) verification factors to gain access to a resource such as an application or an online account.
It is based on one of three types of additional information:
Things you know (knowledge), such as a password or PIN.
Things you have (possession), such as a badge or smartphone.
Things you are (inherence), such as a biometric like fingerprints or voice recognition.