Bei Linux.com gibt es eine Einführung in OpenID.
OpenID is an open decentralized digital identity system that has been gaining traction in recent months. It implements a solution to some everyday headaches such as single-sign-on, but it does not address related issues like privacy, trust, spam prevention, or message authentication. OpenID uses a multiple-stage sign-on process, but don’t let that discourage you. As an end user, the benefits are stacked in your favor.