Macintosh Disk Image
DMG files are used by Mac OS X and are disc image files, usually on a Windows system you will be unable to do anything with these files as they are not supported.
This format supports password protection and compression and is usually used to distribute software over Internet.DMG files are created using utilities in Mac OS X such as Disk Copy in version prior to Mac OS X v10.2 and Disk Utility in later versions. These images can also be burned to CD and DVD.
These files are RAW images with extra layers added regarding the encryption and compression. It is also possible to mount these images a virtual disc.
How to open .dmg files?
Software to open .dmg files
What are .dmg files