What Is a DMG File on Mac?

When dealing with a Macintosh operating system, you will notice that there are a number of files with extensions you may never have seen if you've primarily used Windows computers. These files are in a "proprietary" format, which means they were developed by Apple solely for use with its brand of computers. One of the many different file extensions Mac users will encounter is .DMG.

History

On a Mac computer, a .DMG file is a disk image (the extension is an abbreviation for "disk image"). It is a format designed by Apple. These files are the contents of a CD or DVD compressed into one easy-to-use file. These files can be reburned to physical disc form at any time.

Security

One of the benefits of .DMG files is that they can be password-protected. If you enable this option, nobody can access the contents of the file without the proper authority. This is especially useful if the .DMG file contains sensitive or personal information.

Uses

.DMG files are mainly used for sharing software over the Internet. Instead of tracking down a physical copy of a CD or DVD to install a program from, you can simply download a .DMG file, burn it to a CD or DVD, and perform the installation that way. It also removes the hassle of trying to keep track of many different installation discs.

Creation

You can create a .DMG file using the Disk Utility program. It comes with the Mac operating system, so no additional downloading is required. Simply open the program, load the files you wish to convert into a .DMG, and click on the "Start" button. Disk Utility can also burn .DMG files to CDs and DVDs.

Other Platforms

Though the file extension is designed to be used with the Mac OS, you can download and open .DMG files on a Windows-based computer with programs like TransMac and PowerISO. Linux users can do the same with CDRecord.