If you need to install an operating system such as Linux, Mac OS X or even Microsoft Windows you use a CD/DVD. In certain cases you will download a file that has the .ISO extension. To be able to install the files inside this format, you first need to "burn" (write) the .ISO image on a CD/DVD optical disc. All popular media authoring or disc burning programs will be able to write/burn any .iso file on a CD/DVD but in this short article I will cover all the steps using a popular, free, open-source software named InfraRecorder. In this example, I will show you how to burn an ISO image using the Ubuntu Linux Desktop version. Download and install InfraRecorder on your computer and open the program interface. You have two options to write the image, just click on "Write image" button (see the following image) or go to main program interface and select the third tab named "Action" and choose "Burn Image".

Now, the program will ask you to open the ISO file. Remember where you saved your ISO file (on your computer) and when you find it, select the the file and choose "Open".

As I said, this is an example with Ubuntu Linux but it works for any other ISO file. Take a look at the name of the file in this window. It says "Burn ubuntu-12.10-desktop-i386.iso". If you try to write a different operating system or file you will see something else after "Burn" word. When you're ready choose "OK".
Note: In most cases, InfraRecorder will choose the right CD/DVD optical unit. If your computer has more than 1 unit, choose the one where you inserted a blank CD/DVD disk.

Important: You probably won't see the following error but if you do, here's the explanation for "The data may not fit on the current disc". I attempted to write the Ubuntu ISO file on a CD disk which usually has only 700 MB of space. Since the ISO file has around 771 MB, I need to use a different optical disk, the best example here would be a blank DVD disk. Usually, the CD disk will be ejected automatically if you encounter this error. You will have to repeat all the steps but this time you will need a large disk. In this example, after this error I replaced the blank CD with a blank DVD (which has several GB of space).

If everything was fine, the burning process will start right-away. If you need to modify something and want to cancel the operation, you only have several seconds to hit "Cancel" button, otherwise it will start to write the ISO file.

This is an image of the burning process where you can see the status of entire process: total progress, writing speed and additional messages.
Note: Don't click on "Cancel" button unless you're using a re-writable unit. Even if you noticed or forgot something, canceling the entire operation will make the existing CD/DVD useless - unless it's re-writable.

If the image (.iso file) was burned successfully you will see a similar window and most likely, the application will automatically eject the CD/DVD disk from your computer.

That's how you burn an ISO file using InfraRecorder - it works the same for many operating systems that are delivered in ISO format. If you need more information on how to burn all kind of files with InfraRecorder, check this quick guide.
