When I signed up for WordPress I saw this box labelled Gravatar (Globally Recognised Avatar), uploaded a pic of me which duly appeared in various places on WordPress.
Over the last couple of months I noticed that picture appearing on other sites whenever I made a post. It seems that any site can, if they wish, access the Gravatar database to retrieve your picture. I am reasonably comfortable with that. They also offer a service whereby you can register other sites, including Facebook and LinkedIn, on your Gravatar account. The idea is to demonstrate that the David Ankers on Facebook is the same person on Facebook. That sounds like a good idea but I have not yet seen it working.
Oh yes, and I also changed the settings here so that new posts are automatically notified to Facebook. That might get annoying but I will give it a go.