thumbnail
The thumbnail kioslave is used by for network transparent and persistent generation of thumbnails.
The thumbnail kioslave uses plugins to generate the actual thumbnails. You can enable viewing of these thumbnails from the View Preview submenu, available in or in in file manager mode.
The thumbnail kioslave is not directly useful to a user, but if you are a developer, you can use it within your own applications to create file previews.
See the documentation in the sources for more information. You will find these in the source folder thumbnail