To move an item from one folder to another, just click and drag it to another location in the filesystem. For this, it’s sometimes easier to open two Finder windows, one that contains the item you want to move, and the other set to the location where you want to move it.
If you drop an icon in the same window it started in, its position in the filesystem doesn’t change at all. However, if you’re in Icon View, the position of the icon shifts to wherever you dropped the item.
Dropping an icon into a different folder on the same disk moves the file, while dropping it into a folder located on a different disk copies it, keeping the original file in place while creating a duplicate in the destination folder. This is useful for when you want to copy a folder onto an external FireWire drive or an iPod.
To make a copy of a file or folder, select the item in the Finder view and either:
Hold down the Option key, and drag the item to a new location
Select File→Duplicate (-D) from the menu bar
Select Duplicate from the Action menu in the Finder’s toolbar
When you use the Option-drag combination, the standard mouse pointer changes to an arrow with a little green bubble with a plus-sign inside, as seen in Figure 2-22.
Figure 2-22. Option-drag a file in the Finder to ...