Multi-factor authentication (MFA) increases security for online log in processes. It accomplishes this by requiring a person trying to access an account or service to pass several security checks which are not interlinked. In most cases, two factors are required, and the term two-factor authentication (2FA) is often used in this case.
A service which uses multi-factor authentication may, for example, require both a password plus one or more separate authentication codes. An authentication code may be delivered by SMS, a mobile app, an offline code-generating device, by email, by mail on a printed list, over the telephone, or via other means. In the case, you have to both know the password and have access to the linked phone, email account, code-generating device, or list in order to log in. This means that if a third-party discovers your password, they still will not be able to fraudulently use your accounts without also access authentication codes.
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