When you’re writing blogs, commenting on other people’s blogs and commenting, with others, on your own posts, it’s nice to have a little thumbnail of yourself to show up beside your name. This little thumbnail image is your avatar.
It used to be that you would upload a different avatar at every location on the web that you participate in. But this guy had an idea to make it easier for people to have an avatar that followed them around on the web. It’s called a Gravatar and we recommend signing up for one.
What is it? Well they will probably do a better job explaining it’s features, but I would say this: it’s a free way to associate an avatar with an email account, so that every time you comment on a blog or participate in an online community (that has avatars enabled), your avatar shows up. One caveat is that, although Gravatar has an extensive reach, it’s not infinite – cool thing is that you can extend the reach of your Gravatar through your Gravatar account.