OpenID is the decentralized, lightweight protocol for single sign-on and portable identity that is causing a massive disruption in today’s internet. More than 8,000 Web sites currently accept OpenID, a figure growing by five percent week over week, and many of the world’s leading companies, including Google Blogger, AOL, VeriSign, France Telecom and Sun Microsystems have adopted or announced support for OpenID enabling over 160 million users.

This simple community built technology lets you use your existing presence on the web as a form of identity. It was designed to solve real-world problems around single sign-on, without unnecessary complexity. Just like you can use an email address as a form of identity, OpenID lets you use a web address (URL) that you control to sign in on other sites. And just like email ddresses, you can have more than one, for work, or at home, or for any other use. But unlike email, the sites you use can’t spam you or access your data unless you give them permission.

An OpenID is a URL. An example OpenID URL would be ‘http://bob.myopenid.com/’, and when asked to sign in to an OpenID-enabled site I would type “http://bob.myopenid.com/” into the sign in box.