Multi-factor authentication (MFA) is a process in which a user is requested during a sign-in event for additional forms of identification. This prompt could be to enter a code from a cellphone, use a FIDO2 key, or to provide a fingerprint scan. When you require a second form of authentication, security is enhanced. The additional factor isn’t easily obtained or duplicated by an attacker.

https://learn.microsoft.com/en-us/aspnet/core/security/authentication/mfa?view=aspnetcore-6.0