Google Authenticator is a particularly popular smartphone application that can be used as a token for many two factor authentication (2FA) systems by generating a time-based one time password ...

You'll get a QR code or setup key. Next, open the Google Authenticator app and tap the plus sign. Record the 2FA code/key. Whenever you're asked for the 2FA code, open Google Authenticator to find it.

Google's two-factor authentication application for mobile devices. After logging into a site that uses Authenticator, users receive a phone message with a unique numeric code for that login session.