Google users are now able to secure their accounts with a physical USB security key acting as a second factor in the authentication process. Google has been exploring the possibilities of hardware authentication since 2012. The Security Key is also functional on other websites where the Universal 2nd Factor (U2F) is supported. The key needs to be inserted in the computer`s USB port and tapped, when prompted, to secure accounts using Chrome and Security Key. Learn how to set up it up here. The key is also available on other sites with U2F support.”]
Source: https://www.bitdefender.com/blog/hotforsecurity/google-strengthens-accounts-with-usb-security-key/