But it does it pretty well: it lets your users use their own ids to login to your site. And that’s it. That way you don’t need to manage their usernames and passwords. But any further questions you might have about your user, like “who the heck are they“, “how old are they”, and “can they pay me” are left quietly unsaid. For now.
Love that anonymous OpenID service.
And:
* users don’t have to remember a different username/password for each site, or trust the site owner with the same username/password combo they use for every site.
* someone can know that user X@foo.com really is the X they already know from foo.com, and not an imposter.