Authenticator App by Google

The Google Authenticator App is application that implements security tokens from in mobile apps made by Google (Wikipedia).

2FA or "second factor authentication" is sometimes known as "two-step verification" .

• Google Play - Android App

• iOS - Apple App

Articles

• The Complete Guide to 2-Step Verification

• Getting Gmail Verification Codes Without a Smartphone, or a Phone at All

Also See

• Data Security

• Multi Factor Authentication

• Security

• Safety on the Internet