MFA
In plain terms
Requiring multiple forms of proof to authenticate.
Going deeper
Multi-Factor Authentication combines two or more factors, something you know, have, or are, to greatly strengthen login security. It defends against stolen passwords.
Under the hood
Combines factor types; phishing-resistant methods (passkeys, hardware keys) beat SMS codes.
Examples
Password + authenticator app, hardware keys, biometrics, banking logins.
Think of it like...
Like needing both a key and a fingerprint to open a door.