Should you ever find yourself in the need to create blank disk images, OS X’s built-in Disk Utility is your friend. A disk image usually has a .dmg extension and appears, looks and behaves like any ordinary file, with one key exception: launching it prompts OS X to mount the volume on the desktop.
These mountable disk images can be useful in a number of situations. For example, you may want to create blank disk images for storage.
Furthermore, disk images can be used as a virtual disk for software distribution, to burn CDs or DVDs and so forth. In this step-by-step tutorial, you’ll learn how to create blank disk images in Disk Utility, at any size, with optional password protection, formatting options and more…. Read the rest of this post here