One of the first things I did on my new Mac was go online and download Firefox as it is my browser of choice. The download process was the usual download to your computer but the file had a DMG extension, something I wasn’t familiar with. Being from the Windows world I equated this with an EXE extension and clicked the file assuming the installation would begin. I assumed it was a general installation as an EULA appeared and I accepted then saw the following screen:

I clicked on the Firefox logo assuming this would launch the program and that this window was just showing me Firefox in a folder. I proceeded to use the program believing it was installed and removed the DMG file that was downloaded as I thought it was no longer needed (such as Windows install files). However the next time I went to use Firefox it wouldn’t load, the problem was I didn’t install it.

The DMG file actually “mounts” an image of the program onto your Desktop which looks like this:

If you click on this image it will open the same window as you saw above. What that window is showing you is to move the Firefox icon on the left into your Applications folder — you accomplish this by simply dragging the icon into your folder. You will then see the program start installing. After the installation is complete you are free to move both the DMG file and the Firefox drive image icon into the trash. When you drag the drive image to the trash the trash icon will switch to an eject button and this will be discussed in a later post.

Most programs downloaded from the Internet will have this DMG extension and will feature an install window which varies by program. Some are more intuitive on what you should do and some are a little more abstract such as the Firefox one. For example, below is the install window for Adobe Lightroom Beta 4.

As you can see, this install shows the movement of Lightroom into the Applications folder with a bolder arrow. However if you didn’t know that you actually had to drag the icon into the folder you still might make the same mistake I did when I first tried installing my first downloads on the new Mac.

Installation of programs is as simple as dragging the icon into the Applications folder, no further steps are needed. It really is that easy.