A Gravatar is your profile on the web, and the Hovercard is one way your information is made visible to others. It’s an easy way to help people find your blog, or access your identity on other services like Twitter, Facebook, or Linkedin.
Viewing a Hovercard
Hovercards appear when you place your mouse over any Gravatar. Here’s an example of what it looks like:
Viewing your Hovercard
Go to Settings -> Discussions in your Dashboard, and scroll down to the Avatar section. You will see a sample of your Hovercard. You can also just look at any comment you’ve left on another WordPress.com blog.
Turning off Hovercards on your blog
You can turn off Hovercards by going to Settings -> Discussions, and scroll down to the Avatar section. You’ll see a checkbox for Gravatar Hovercards. This will disable hovercards on your blog.
Turning off Hovercards for all WordPress.com blogs
As a visitor you can disable all Hovercards by clicking on Turn off hovercards in the bottom right corner of any Hovercard.
Note: That this only disables it for you, not for anyone else.
To re-enable Hovercards that have been disabled with the Turn off hovercards option you will need to delete the cookie nohovercard from the domain .wordpress.com.
If you are unsure about how to clear individual cookies you can visit this site for details of removing cookies for various browsers.