In one sentence: Multi-factor authentication (MFA) means signing in with two or more different kinds of proof, such as a password plus a code from an app.
Why it matters: It is the same idea as two-factor authentication, with more than two steps possible. Each extra step makes it harder for a criminal with only your password. Some sites and agencies, such as the US agency CISA, use the name MFA.
One thing to do: Pick one account, such as your bank or email, and turn on any extra sign-in step it offers.
Related terms: two-factor authentication, passkey, security key
Learn more: Two-Factor Authentication (2FA): What It Is and How to Turn It On
Checked: 25 Oct 2026. Settings screens change. If yours looks different, search the company's help page.
