When a portlet supports Edit mode, an icon with a pencil 
appears in the title bar
of the portlet. Edit mode is where you specify any information necessary for the portlet
to operate when placed on a custom page. Edit mode is also where preferences can be
selected. Preferences provide a way to customize a portlet to control the amount of
detail displayed.
Clicking on the icon replaces the portlet content with preferences for the portlet. (Examples include sort order and subset capabilities.) Preferences are stored on a per user basis and retained after the session ends; they are not shared between users.