SPIEGEL ONLINE has introduced Facebook's Recommend button, enabling you to easily share articles and tell your friends about them. Just click on the button at the top of a story and a new window will open up allowing you to log-in to Facebook. When you do that, a Facebook cookie will be set on your computer. If you do not click the button or have not logged-in to Facebook, then no Facebook cookie will be set on your computer.
If you are a Facebook user, have logged into the service and then hit the Recommend button, this information will then be shared on your Facebook profile. Other users can then see that you have shared an article. You can determine which users have access to this information by adjusting your Facebook privacy settings.
If you visit a page that includes the Recommend button, the IP address will be shared with Facebook, but it will be anonymized in a way that will preclude the possibility of determining the computer or the identity of its user.