Two-factor authentication (2FA) is a security method in which the user confirms their identity by entering two different verifiable pieces of information from different categories. These categories include knowledge factors, possession factors, and inherent factors.
The user enters the first verifiable piece of information: this can be a password or a PIN (knowledge factor). After the first piece of information has been entered successfully, the system requests a second verifiable piece of information. This may be a one-time password (possession factor) or a fingerprint (inherent factor). It then compares both pieces of information with the stored authentication data. If both match, the system grants the user access; if they do not match, it denies access.
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Two-factor authentication (2FA) is used in many areas. It increases security when accessing systems and services, for example in the following contexts:
Bank accounts: In addition to their password, customers enter a code sent to their mobile phone. Only then can they access their online banking account.
Credit card transactions: When shopping online, users may need to enter a code. The code is sent to their registered phone number to confirm the transaction.
VPN access: In addition to their password, employees enter a code provided via an authenticator app or by SMS. They can then access the corporate network.
Electronic health record: In addition to their password, doctors and patients enter a code. They receive it by SMS or via an authenticator app. This provides better protection for access to sensitive health data.
More information is available here on two-factor authentication.