What is an ISO file? Definition and functions

Creating an ISO file involves copying file systems, programs, and data to the ISO file format using a suitable ISO tool, typically an optical storage image that is not bound to any physical media.

The term ‘ISO file’ or ‘ISO image’ goes back to the standardised format ISO 9660 or 13346 for CD-ROM media and stands for the identical storage image of optical media. An ISO file thus contains all the same data you would transfer when copying data to CD, DVD, or Blu-ray. Unlike archive files in ZIP or RAR format, the binary copy is not compressed, but is exactly the same as the original in terms of storage size, structure, permissions, and metadata. When opening an ISO file, you ‘mount’ the memory image from a CD/DVD, a bootable USB stick, or a virtual drive.

ISO file creation has several advantages:

1. No physical disks: When you’re using important data, software, or operating systems in the form of an ISO file, you don’t need to store any physical data carriers to recover the data. You can simply store and archive large files including photos or videos as ISO files on external, local, or USB drives.
2. Fast access: Opening an ISO file is easy enough. Use the Finder in macOS or right-click ‘Deploy’ in Windows (as of Windows 8). In Linux/Ubuntu you can open or ‘mount’ an ISO via the terminal as a new virtual drive. In older Windows versions, a suitable software like WinZip or 7-Zip is needed.
3. No need for optical drives: Since newer computers tend to be manufactured without a CD and DVD drive, ISO files enable you to reuse and back up your original archives and memory images. You won’t need to rely on CDs and can use files remotely from your drive without an external data carrier.
4. Simple creation of multiple copies: To create multiple copies, you don’t require multiple drives when copying ISOs.

What you use an ISO file for mirrors whatever you would use CDs/DVDs/Blu-rays for. ISO files support the archiving of file folders such as system and installation files of operating systems, software programs, file folders, movies, videos, or even computer games. ISOs are popular among gamers into older classic games (e.g. SNES or Playstation 2) based on PC emulators.

They are also handy for running and using multiple guest operating systems via hypervisor or virtual machine monitors. If you don’t have a CD/DVD drive but want to use a guest system on your device, you can still run it using ISO files. All you need to do is create an installation medium in the form of a bootable USB stick with an ISO. Always make sure that you have sufficient storage space on the target media, since ISO files require more memory compared to an original source.

In Windows, you can create an ISO file with the Media Creation Tool. If you haven’t downloaded it yet, you can do so from Microsoft’s website for free. Follow the instructions of the Windows tool wizard to create an ISO for Windows 10 or 11 or install upgrades. This works in Windows as well as Linux and Mac. However, you can use a Windows ISO for operating systems only with a valid license and product key.

To create ISOs from files, programs, or systems, it is best to use programs such as IMGBurn or CDBurnerXP. Install the burning software, insert the data medium to create an ISO file from, and configure the settings including the storage location. If you don’t have a CD/DVD drive, external drive, or original media, you can also download ISO files online and create a bootable or even multi-bootable USB stick from them. This works for all Windows versions from Windows 7 to 10 and Office 2010 to 2019 with the Windows ISO Downloader, which automatically searches for all Windows system files online and creates ISOs from them.

If you already have an ISO file, but want to create an ISO CD or ISO USB stick from it, just use the Windows on-board resources. To do this, you need a CD/DVD or USB drive and the corresponding data medium from which you want to create an ISO installation medium. Locate the ISO file in Windows, right-click and burn the ISO via ‘Open with...’ and ‘Windows burner for disk images’.