As before, the sign-in requires a Bluetooth connection between the 'key' and sign-in device in order to thwart remote account hijacks. You can register a backup key as a safeguard in case you lose your phone.

Advanced Protection was primarily designed for political figures, celebrities, journalists and others who are more likely to be targets of hacking attempts. Google is rolling this out with those users in mind, especially with the 2020 US presidential election on the horizon. However, the company makes clear that this is available to anyone. If you're concerned enough about your account that ordinary two-factor authentication isn't enough, you're encouraged to sign up.