Drag and Drop is a method of moving or copying a file or several files using the mouse or touchpad.
By default, if you left-click and HOLD the left mouse or touchpad button while moving your mouse pointer to a different folder location on the same drive, when you release the left mouse button the file is moved to the new location where you released the mouse button.
If you are moving the file to a different drive or across the network to a mapped drive or another device, the file is COPIED to the target location, and the original file remains in the original location.