What is OpenID:
OpenID is an open, decentralized, free framework for user-centric digital identity.
OpenID starts with the concept that anyone can identify themselves on the Internet the same way websites do-with a URI (also called a URL or web address). Since URIs are at the very core of Web architecture, they provide a solid foundation for user-centric identity.
To start using OpenID you need to first register with a OpenID service provide like ClaimID or using OpenID framework you can create yourself one without bothering about third party sites. Once you create OpenID, use that ID for future registrations and logons in OpenID enabled websites. For example you want to register ate ma.gnolia.com you can enter your OpenID there, it will take you to your OpenID provider, after authentication is done you will be taken back to Technorati.
Still confused, watch the video: