How to make iso file br The easiest way to think of an ISO file is more like a .zip or .cab archive file, only without the compression. br An ISO file contains the image of a disk. That means it contains all the files and folders that were on that disk, much like a .zip or .cab file contains a collection of files and folders. The real difference is that an ISO is a byte-for-byte copy of the low-level data actually stored on a disk.