When I try to move the folder, the copying process begins Why, when I move (using mouse) one folder into another, instead of moving, copying process starts? How to fix it?

OS X El Capitan
Folders are located on an external drive, GUID partition scheme, connected via USB.
Hold the  Cmd ⌘  key as you drag.
This will reverse the default behaviour of 'move to same drive, copy to another'