Common
It leaves the referer unaffected if you the user moves through the same or subsequent path.
This option may be enabled if user movement should be hidden, but there are services that rely on a referer to work properly.
—if the domain is different
If this option is enabled a referer is removed in case the user came from a different Web site.
It leaves the referer unaffected if the user moves through the same Web site.
This allows the Webmaster to track user movement through this Web site. The information may be useful for adjusting or optimizing the nav- igational structure of the site.
As well, some services such as online banking may need a referer to work properly.
Prefix Filter
The Prefix Filter section looks like this:
Using this section, you can configure a filter to remove all prefixes from URLs that are used by some sites to track user behavior.
If you want to use this filter, make sure the checkbox next to the section heading is marked. The checkbox is marked by default.
After modifying this setting, click on Apply Changes to make the modification effective.