In a nutshell, OpenID lets you create one username and password you can use on thousands of Web sites, simplifying your online experience. There are a lot of big names involved, including Yahoo!, AOL, Facebook, PayPal, Google and Microsoft.
With OpenID, your password is only given to your identity provider, and that provider then confirms your identity to the websites you visit. Other than your provider, no website ever sees your password, so you don’t need to worry about an unscrupulous or insecure website compromising your identity.
Today it is estimated that there are over one billion OpenID enabled user names/passwords and over 50 thousand sites supporting OpenID logins. You may even have one already, if you have an AOL screenname or a Yahoo! login, for example. To find out more about where OpenID can be used and how to get one, visit the OpenID official website at http://openID.net .
Some advice regarding OpenID : If you are going to trust everything to one username/password, you need to be really sure it is safe. With OpenID , your security depends on where you first sign up for it. When you login, other websites will go back to your original OpenID registration site to check your username/password. Try to find a registration site that offers the option of a personal security device for your online safety, such as Yahoo! for example.
Another option to consider is to use OpenID or InfoCard providers that offer a stronger authentication process, such as a secure USB token rather than password recognition.