[nepenthe]

Sorry I was not clear and it is not terribly important. I've just wondered what it actually means to be "registered." If I have recovered my cookie-based account it means the account has been verified by e-mail. I'm just wondering isn't that a form of registration without having to have used OpenID?

[kmontrose]

Its mostly a distinction between "can login with one click (Registered with OpenId/Facebook)" and "can login with a crazy convoluted path (provide email [again], check email for link, etc.) (Unregistered)".

You can get the lion's share of a Stack Exchange's utility without registering, and this is quite intentional.