What is OpenID?
OpenID is an open standard that lets you sign in to other sites on the Web using your WordPress.com account. This means less usernames and passwords to remember and less time spent signing up for new sites.
What is my OpenID?
Your openID is your blog URL, i.e. http://yourblog.wordpress.com/
How to use OpenID?
1) Enter your blog URL on the sites that allow openID.
2) Click the ‘Sign In’ button and you will be redirected to WordPress.com. If you are already logged in, you will be asked if you want to pass your identity to the site.
3) Click “Yes; just this time”, or “Yes; always” if you don’t want to be asked this question again for this site.
4) You will be redirected back to the site and logged in, all without using a username or password!
On which sites I can use my OpenID?
Click here to get the list of sites that accepts the OpenID.