!!! Overview
[{$pagename}] is part of the [FIDO] Alliance and is designed to allow online services to augment the security of their existing password infrastructure by adding a strong second factor to user login. The user logs in with a username and password as before. The service can also prompt the user to present a second factor device at any time it chooses. The strong [Multi-Factor Authentication] ([2FA]) allows the service to simplify its [Passwords] (e.g. 4–digit [PIN]) without compromising security. 

[{$pagename}] originally developed by [Google] and [Yubico] became a [FIDO] [standard] alongside the original [FIDO] [UAF].  

[{$pagename}] really has two parts a [JavaScript] [API] (now [WebAuthN]) for [Relying Party] to [browser] and a [browser] to [authenticator] potion both were called [{$pagename}] but now the [Client To Authenticator Protocol] ([CTAP2])

[{$pagename}] [Authenticators] when used with [WebAuthN] SHOULD only allow usages as [2FA] and not as primary [Authentication]

!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]