Your Gravatar is the image that follows you around from site to site. Many of the sites you join or interact with will pull your image from gravatar.com by default. They help people identify you and add credibility. This is especially true in the blogosphere and its many comments.
It only takes 5 minutes to set up your gravatar… if you have a “headshot” or the equivalent ready to go.
1) Make sure anyone who authors content in your blog or website has a gravatar account
2) Gravatars are delivered based upon your email address. If you use multiple email addresses, make sure each one is accounted for.
3) When you sign-up, you use your WordPress.com account.
Resources:
Step by Step instructions for setting up your Gravatar
Gravatar.com to signup