An authentication factor is a category of evidence used to verify identity. Multifactor authentication (MFA) strengthens access by requiring at least two different factor types instead of trusting a username and password alone. section 6.5
The three factor categories are:
- Something you know, such as a username and password. section 6.5
- Something you have, such as a phone with an authenticator app or a hardware security key. section 6.5
- Something you are, such as a fingerprint or face scan. section 6.5
Requiring multiple factors limits the damage from reused, exposed, or weak passwords. In Azure, administrators configure the requirement through Entra ID Security and Conditional Access policies. section 6.5

