Google today expanded two-factor authentication (2FA) for Google account users and opened the door for other websites to offer 2FA to customers who visit their sites through Google Chrome. Chrome is the first browser to implement support for Fast Identity Online (FIDO) Universal Two-Factor (U2F) Authentication. The drawback of Security Key is that it only works on devices that have USB ports — thereby counting out most mobile phones and Apple devices. Google will continue to offer Google account holders its existing 2FA method, which a user manually enters a six-digit code sent to their mobile phone.”]
Source: https://www.darkreading.com/cloud/google-expands-2-factor-authentication-for-chrome-gmail