Complex sentence: Smart Uninstaller removes widgets, applications, preference panes and plugins and their associated preferences, web caches and log files which still remain on the Mac's hard drive even after the item has been removed to the trash.
Split into simpler sentences: Smart Uninstaller removes widgets, applications, preference panes and plugins. It removes the preferences, web caches and log files which still remain on the Mac's hard drive even after the item has been removed to the trash.