Two-factor Authentication is not an uncommon term in the current digital climate. 2FA typically requires authentication processes that require two of the following three identifiers: something that you know (like a username and password combination), something that you have (such as your laptop, mobile phone, or external hardware token), or something that you are (such as your retinal scan, fingerprint or facial structure). The use of two distinct authentication factors increases security by adding another, exponentially more difficult to crack barrier for potential attackers, while reducing the threat inherent in relying simply on a potential weak and unsecure password.
Of course, the method of delivery for the second factor is much more detailed than simply providing a piece of hardware, alongside your typical login credentials – with the exception of biometric 2FA which only requires your presence. Typical 2FA involves the delivery of a single-use, constantly changing code called a One-time Password(OTP).