OpenID is a decentralized and free single sign on system.
In order to obtain an OpenID for yourself you should first claim one from sites like e.g. http://www.myopenid.com.
To keep control which OpenID provider you are using turn your web page into an OpenID. This is possible by adding
<link rel="openid.server" href="http://www.myopenid.com/server"> <link rel="openid.delegate" href="http://user.name.myopenid.com">
into the header of the html page.
If you use servers other than myopenid.com Replace the openid.delegate href with your OpenID , and the openid.server href with the server of you OpenID provider. You can find this server by viewing the source of your HTML page on your provider's site.
You can lean more about OpenID at: