What is OpenID?

In recent days, I see the word openID in many sites. OpenID, what is it?

Here is the answer. OpenID eliminates the need for multiple usernames across different websites, simplifying your online experience. OpenId is an open, decentralized standard for user authentication and access control, allowing users to log onto many services with the same digital identity . In simple, Common userId for different websites where you have accounts. For more information see http://openid.net/