What is Two-Factor Authentication?

What is Two-Factor Authentication? - illustrated definition card

Two-factor authentication (2FA) adds a second proof of identity at login — a code from an app, a text message, or a hardware key — so a stolen password alone can't open your account.

Enable it in each account's security settings, preferring an authenticator app or passkey over SMS (phone numbers can be hijacked). It's the single highest-value security setting on any account you care about.