Whenever you are commenting on a blog, you probably see that some people have their photo by their comment, whereas others have a grey default avatar.
Gravatar is a site that is plugged into most blogging platforms – it attaches an image to commenters via their email. When you register with a particular email address and upload a photo, it will post that photo next to any comments you make on blogs supporting Gravatar images using that email.
Why is this important? Comment spam bots typically do not have Gravatars, so having a photo next to your comment will make you look more like a person and less like a spammer. It’s a fast, easy and free service to sign up for, and all you have to do to use it in the future is use the same email address when you make comments.