Q: What exactly is an ISO file?
A: ISO images end with the file extension ISO. The letters ISO represent the International Standards Organization, or as it is more commonly known, the International Organization for Standardization. This organization is based in Switzerland, and it sets most of the international standards that we use in technology.
I have heard ISO pronounced as "EYE-so" as well as "eye-es-oh." Regardless of how you pronounce it, the letters indicate the organization from Switzerland. By the way, the letters have nothing to do with the Greek "isos." Visit www.iso.org for more information.
One ISO standard is ISO-9660, which outlines how files are saved to optical media (such CD-ROM or DVD). This file system is called — not surprisingly — the Compact Disc File System (CDFS). Thanks to the ISO, a Windows computer can read the same CD or DVD that a Macintosh or Linux computer can read despite that each of these three uses a different file system on the hard drive. Windows uses NTFS (New Technology File System), Macintosh uses HFS (Hierarchical File System, such as OSX), and Linux uses EXT2. However, they can each read the same CD or DVD placed into the computer’s tray. Thank goodness for the ISO!
But why should we care about ISO-9660? Let me give you a scenario:
You just bought one of those cute netbooks. It’s small, but it has a real QWERTY keyboard on it (QWERTY, of course, are the first letters of the top row on keyboards used in the United States. Catchy name, isn’t it?). However, your netbook does not have a CD-ROM drive. So how do you install your programs that come on CD-ROM or DVD? We turn to ISO-9660 for help.
You can place an image of your program onto a flash drive and install the program that way. But the greatest feature of the ISO-9660 is that you can make an ISO image of your Windows 7 or Windows 8 installation DVD and place that ISO file onto a flash drive. You can then make that flash drive bootable so that you can install a fresh copy of the operating system. Thanks again, ISO!
You can think of an ISO file as a box that holds all the parts to something that needs to be built — such as a child’s toy you might buy that requires assembly. The box holding the toy pieces does you no good as an actual toy, but the contents inside of it, once taken out and put together, become what you're actually wanting to use.
An ISO file is the same way. The file itself is no good unless it can be opened, assembled and used. The most common way to make use of an ISO file is to burn it to a CD or DVD. It's a different process than burning several music or document files to a disc because your CD/DVD burning software must "assemble" the contents of the ISO file onto the disc.
ISO image files are often used to distribute large programs over the Internet. This is because all of the program's files can be neatly contained as a single file — the ISO file. Even Windows 8 and Windows 7 can be purchased directly from Microsoft in ISO format.
What? You don’t know how to make a bootable flash drive using an ISO image? Keep your eyes on this column, and I’ll show you how.