[zachsnow]

That website is very bad at conveying what it actually is to someone that might want to use it.

[RugnirViking]

Indeed. I spent 10 or 15 minutes trying to figure out if they are selling a physical device, like a usb 'key' or are just selling 2 factor authentication with mobile phones. And I'm still none the wiser. It's pages upon pages of buzzwords and nonsense.

[Godel_unicode]

That's because it's not either-or. Read more slowly, it's a wide-ranging spec and there are many different implementations/extensions.