A Gravatar is a type of avatar, or personal image, that’s used across many Web sites and recognized by people around the world. An avatar appears next to your username when you post comments or messages to online forums and blogs. An avatar is a type of “digital signature” that distinguishes you from other users and helps you stand out from the crowd. Avatars help users recognize one another and build community.
A gravatar is a globally-recognized avatar. It appears next to the comments you author on WordPress blogs and sites that use Discus. Hootsuite also uses gravatars. Over time, gravatars help active users build their brands and online reputations.
You can create a gravatar by signing in with your WordPress account at Gravatar.com, then uploading a photo or company logo. The site will ask you to add a rating for the image. The ratings are similar to those used for movies; they include G, PG, R, or X. If you don’t create a gravatar, a generic icon will appear next to the comments and messages you post.
Some WordPress themes include gravatars in their designs. Administrators can control gravatars under the Settings | Discussion option in the Administration Area. For example, they can set gravatars to display or not display, and filter them by rating.