What is the .dmg file that always appears on my desktop when I download?

its the installer file

you can delete it once youve installed the programs

To expand a little bit. It's a disc image. Hence the .dmg name. When you click on it it will mount just like any other disc (CD, DVD, volume, etc.) and once it's mounted on the desktop you can drag the file/application to the appropriate place and then command/click on it and eject it and Trash the file.

yea what he said

If you are a windows person, a .dmg file is the Mac version of a .iso file in windows. Basically its a image of program that is formatted so it can be burned to a disc. The file extension should be associated with whatever disc burning program you are using.

On a side note, the .dmg file wont work in windows, and vice versa, a .iso file wont work in Mac. You need a third party program like UltraIso to convert them. If you convert them make sure you run a checksum on the file to ensure you get an accurate conversion. When you are crunching that many numbers sometimes things get screwed up.

Cheers 🙂

Lol I got completly off topic. No you dont have to keep them. Once the program is installed you dont need the .dmg file to use the program. But I would suggest burning them to a disc so you have a backup and dont have to re download them again in the future.

Best way to think of a dmg file is like a virtual CD-ROM. When you double click it, it appears in the Finder sidebar, just like a CD-ROM does when you insert it.

You can now install the app, either by running the installer (if there is one), or just dragging the app's icon to your applications folder.

Once you're done, 'eject' the dmg by clicking the little eject button next to it, and drop it in the trash if you don't need it anymore.

If you are a windows person, a .dmg file is the Mac
version of a .iso file in windows. Basically its a
image of program that is formatted so it can be
burned to a disc. The file extension should be
associated with whatever disc burning program you are
using.

On a side note, the .dmg file wont work in windows,
and vice versa, a .iso file wont work in Mac. You
need a third party program like UltraIso to convert
them. If you convert them make sure you run a
checksum on the file to ensure you get an accurate
conversion. When you are crunching that many numbers
sometimes things get screwed up.

Cheers 🙂

iso files do work on a Macintosh