In case you’re wondering what all those little silhouette icons are about, they are placeholders for folks with no avatar.
An avatar is a graphical representation you provide to give others some kind of insight into who you are. In this largely anonymous “interworld” it can provide a way to let folks know that you’re not (or maybe you are) overly serious. Or maybe you’re a cat lover… whatever you want to express.
This site supports a particular type of avatar called a gravatar. A gravatar is a globally recognized avatar. You can go to their site and register one or a few of your email addresses (they don’t have to be your primary address, just one that you’d provide to blogs and forums you frequent) and then put up your avatar image there.
Any blog or forum that supports gravatars, once you’ve provided one of your email addresses, will then show the relevant avatar sourced from the gravatar site.
You can even specify “G” through “X” so that you can have different images on differently oriented sites. My site supports up to an “R” rating.