Twitter users can now protect their accounts with FIDO U2F 2FA using a YubiKey. This new feature is now available to all 328 million of Twitter’s monthly active users for both personal and business accounts. Once you register your YubiKey with Twitter, you will be required to present the key each time you login to your account in the future. It will ask for your username and password, and then it will ask for your YubiKey. Just insert the YubiKey into your computer’s USB port and after it starts blinking, tap it.