What is "google-openid"

Openid is an identification system developed by Brad Fitzpatrick of the Livejournal. It is a distributed network in which the identity of the user is given by a URL or XRI that can be verified by any server running the protocol.

On websites that support Openid, users do not need to create a new account before they can access it. You only need authentication by a site that supports Openid, called an identity provider. This provider can then confirm the Openid owner for another site that supports Openid.

Independent of single Sign-on architectures, Openid does not define an authentication mechanism. So the strength of an Openid login depends on how much the site knows about the identity provider’s authentication policies. Without such trust, Openid is not recommended to be used with sensitive accounts such as e-commerce and banks.

Link to official page: http://openid.net/