BuddyPress.org

Last time I looked at how Gravatar works, it was like this: A URL is built with a parameter tacked on. The parameter is a ‘hash’ of the user’s email address. That URL is embedded into an <img src…> tag.

When someone’s browser tries to render the image Gravatar is contacted. Gravatar then checks to see if the email address has an avatar (stored at Gravatar) associated with it. If it does it returns that avatar and if not it returns a default image instead.

So in either case a browser waits on Gravatar to dump out an image file.