OAUTH2 is a fancy mechanism for apps/websites/etc to delegate arbitrarily complex multi-factor login capabilities to a central authentication management web site. It is primarily driven by Google for use in mobile-phone-based apps, but can be used in other ways as well.
This is a companion discussion topic for the original entry at https://copr.fedorainfracloud.org/coprs/nurmukhamed/cyrus-sasl-xoauth2/