Like many people, I have a WordPress blog, and I ask my readers to identify themselves when they post comments by authorizing WordPress to access their Facebook or Twitter profiles. This helps me filter out anonymous trolls and spammers.
But it is an option not all users appreciate. Twitter user @herminones reached out to me, saying:
Oleg, I would have liked to comment on your most recent blog but for the pre-requisite WordPress Faustian contract
The option to rely on Facebook or Twitter is not unique to WordPress. Authentication, authorization and password management are some of the key APIs of any useful application. As a result, many apps authenticate via Facebook, Twitter, or another third-party identity provider.