What is Multi-Factor Authentication (MFA)?
A ground-up, beginner-friendly deep dive into how Multi-Factor Authentication actually works under the hood: the front-door-key-and-fingerprint analogy for why one secret is never enough, the six-milestone historical arc from the 1986 RSA SecurID hardware token through HOTP (RFC 4226) and TOTP (RFC 6238) standardization, push-notification MFA, U2F/WebAuthn, and today’s passwordless…