Shell extensions are those commands added by third party programs to the menu that appears when you click the right button of your mouse. WinZip "Add to zip file..." command is a good example of a shell extension. A more technical explanation: http://en.wikipedia.org/wiki/Shell_extension
Well, RegSupreme can help you to remove those shell extensions you don't need. For example, say Winamp adds these entries to the shell menu "Add to playlist", "Play" and "Enqueue", and you decide that the entry "Add to playlist" is useless and you just want to play your music. With RegSupreme you can delete the entries you actually don't need ("Add to playlist" in this example) and this way you reduce clutter in your shell menu. You'll be amazed to see how many entries can third party programs add to this menu
Doesn't RegSupreme Pro helpfile explain something about these entries?