Two-Factor Authentication (2FA)
2FA uses exactly two different authentication factors.
Updated: 2026-03-05
Definition
Two-Factor Authentication (2FA) requires two different factor types, such as a password (something you know) plus a one-time code from an authenticator app (something you have).
2FA is a specific form of MFA (MFA can include two or more factors).
Key points
- Two different factor types are required (not two passwords)
- TOTP and hardware keys are common second factors
- Better than single-factor, but still needs secure recovery
Common mistakes
- Calling 'password + security question' a second factor (it’s still 'something you know').
- Ignoring account recovery security (weak recovery can bypass 2FA).
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