What’s an ISO and why do you “burn it”
Nowadays if you want to install an operating system, be it Linux or Windows, most of the time you’ll go to the manufacturer’s website in order to get an ISO image. An ISO image (also called an ISO file) is a file format standard which allows you to store all the information found in an optical disk, like a CD or a DVD, in a digital file. The format is named after the standard which specifies it, the ISO 9660 standard. In short, ISO images allow you to turn any optimal media into a digital file (something extremely helpful in today’s world where optical media drives are almost nowhere to be found).
Since these ISO images emulate perfectly an optical disk, most operating systems out there are offered through their developer’s website in ISO files, it’s your job then to “burn” these ISO files to a USB stick or memory card and install the operating system from there.
The term “burning an ISO” is an old legacy of the time when information was “burned” (literally) on CDs or DVDs. Back then a laser burned the surface of the CD or DVD in order to record the information on the tracks contained on the optical media’s surface. CDs and DVDs are becoming something obsolete in the present, but the term just stuck with people and is still popularly used even if “burning an ISO” to a USB stick just means copying the files.
Burning an ISO in Windows
Step 1: get the ISO image
Download the ISO image of your operating system of choice. Either with Windows, Linux or Raspbian you can get these ISO images by going to the respective operating system’s website. Microsoft’s Windows distribution site is called the Software Download site (check the next subsection if you’re already on Windows and Microsoft isn’t letting you download a Windows image). You can download nearly every Linux distro image from Distro Watch.
Step 2: download and install Rufus
The best tool to burn ISO images to a USB stick in Windows is completely free and relatively small (just 1.1 megabyte). This is the Rufus ISO burning tool.
Step 3: Configure Rufus
Rufus will auto-detect your USB stick, but if you have multiple USB sticks plugged into your system you’ll have to select the correct one from a drop down menu. Then your next step is to select the proper ISO image to burn.
Lastly, and perhaps the most confusing part to most people is choosing the Partition Scheme and Target System (BIOS type). If your machine was built somewhere during the past 5 or 7 years just choose GPT for the Partition Scheme and UEFI for your target system.
If your machine is very old choose MBR for your Partition scheme and non-UEFI for the BIOS type. Don’t worry if you don’t choose the right type, nothing bad will happen to your machine the USB stick will just fail to boot. Remove it and re-burn it.
The other options are relatively irrelevant. Volume Label is just the name the USB will have after burning it. You can leave File System set to FAT32 and Cluster Size set to 8192 bytes. These two values work for literally 99% of the cases.
Getting a full Windows ISO image on Windows
For some reason if you go to Microsoft’s Windows download site using a Windows PC instead of getting an ISO image of Windows Microsoft will let you download the Windows Download Tool instead of the actual ISO file. This is not the case if you go to the site with a non-Windows device. In that case Microsoft will allow you to download the full ISO image.
So, if you want Windows’ full ISO image instead of the download tool, just go to Microsoft’s Download Site with your tablet, phone or non-Windows laptop/PC and download the ISO image, then transfer it to your Windows PC in order to burn the ISO to a USB stick.
Burning an ISO in Linux
The process of burning an ISO in Linux is much easier since you don’t need to download any additional software, you can use Linux built-in commands in order to do it.
On Linux everything is represented as a file, even all hardware. This means hard disks and USB sticks can be accessed as files. The dd command can read and/or write from/to these files, and we can use dd to transfer information from a device to another and perform conversions on the data as it copies it.
In order to burn an ISO to a USB stick in Linux with dd we need to input the following commands:
# Find the USB device
sudo fdisk -lAs we can see in this example, our USB is represented by the file /dev/sdb
For this example we assume the ISO image is called file.iso and is located in your home directory.
sudo dd bs=4M if=~/file.iso of=/dev/sdb