Your Gravatar is an image and public profile that follows you from site to site appearing beside your name when you do things like comment or post on a blog. Avatars help identify your posts on blogs and web forums, so why not on any site?

Gravatar (a portmanteau of globally recognized avatar) is a service for providing globally unique avatars and was created by Tom Preston-Werner. Since 2007, it has been owned by Automattic, having integrated it into their blogging platform.

Ronald Soh @ Gravatar