HTTP Referers
This features allows you to know from which website your visitors are coming.
The filter notion allows to regroup the referers : if filter=50 then the regroupment will be done using the 50 first caracters.
You may end up with an important list if you don't administrate this section daily. You can turn this feature off in the preferences.
You can also set a maximum number of referents before you receive an error message
You can archive or delete the list (directory : slogs/referers.log).