MFA (2FA, multi-factor authentication)

Logging in with two or more kinds of proof, such as a password plus a code from an app or a security key.

A stolen or reused password alone is then not enough. Factors differ in strength: SMS codes can be intercepted or ported, app codes can be phished on a fake page, while security keys and passkeys are tied to the real site and resist phishing. In companies, MFA is usually enforced once, at the identity provider, through SSO.

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Related terms

Passkeys: Passwordless login with a key pair stored on your device or password manager, unlocked by fingerprint, face or PIN.
SSO (single sign-on): Logging in once with a company account (Microsoft, Google, Okta) to use many apps, managed centrally by IT.
OAuth: A standard that lets an app act on a user’s account elsewhere (mail, calendar, files) without ever seeing the password.

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