Two-factor authentication (2FA) and multi-factor authentication (MFA) are high-security measures that can be enabled on a user account to prevent authorised access. They ensure that the user proves that he has the right to the account by asking him to provide information known to only him (knowledge), a password or some other code delivered to only him (possession), or/and a unique character such as his fingerprint (inherent).
In 2FA, only two of the above factors are used to verify the identity of the person trying to access the account to complete a transaction online, while in MFA, two or all three factors can be used for verification.