Gravatars and avatars are popular all over the web today, especially on blogging sites. Gravatars and avatars are icon, or graphic representation, of a user in a shared virtual reality, such as a forum, chat, website, or any other form of online community in which the user(s) wish to have something to distinguish themselves from other users.
WordPress makes it easy to use gravatars and avatars on WordPress sites in the comments template file. This allows a graphic representation of the comment author to be visible next to their comment. For more information on how to add gravatars to your WordPress site, check out Using Gravatars.