The Free On-line Dictionary of Computing (30 December 2018):

drag and drop
drag
dragging

   A common method for manipulating files (and sometimes text)
   under a graphical user interface or WIMP environment.  The
   user moves the pointer over an icon representing a file and
   presses a mouse button.  He holds the button down while moving
   the pointer (dragging the file) to another place, usually a
   directory viewer or an icon for some application program,
   and then releases the button (dropping the file).  The meaning
   of this action can often be modified by holding certain keys
   on the keyboard at the same time.

   Some systems also use this technique for objects other than
   files, e.g. portions of text in a word processor.

   The biggest problem with drag and drop is does it mean "copy"
   or "move"?  The answer to this question is not intuitively
   evident, and there is no consensus for which is the right
   answer.  The same vendor even makes it move in some cases and
   copy in others.  Not being sure whether an operation is copy
   or move will cause you to check very often, perhaps every time
   if you need to be certain.  Mistakes can be costly.  People
   make mistakes all the time with drag and drop.  Human
   computer interaction studies show a higher failure rate for
   such operations, but also a higher "forgiveness rate" (users
   think "silly me") than failures with commands (users think
   "stupid machine").  Overall, drag and drop took some 40 times
   longer to do than single-key commands.

   [Erik Naggum ]

   (2007-06-15)