ISO 9660 is a filesystem designed for use on CD-ROMs. An “ISO image” is a file that contains an ISO 9660 filesystem and can be burnt to a CD.

ISO 9660 is the standard filesystem for use on data CDs. It is commonly known as “ISO” for short. An “ISO image” is a file that contains an ISO 9660 filesystem.

ISO 9660 has several restrictions that are similar to MS-DOS FAT, in particular with file names consisting of 8 characters, a dot and 3 characters (the details of the restrictions are different, though). There are two common extensions that among other things allow longer file names:

  • Joliet allows 64 Unicode characters in a file name (UCS-2 only). It is supported by most unices and by Windows.
  • Rock Ridge allows 255-byte file names and supports symbolic links, permissions and other traditional unix metadata. It is supported by most unices.

To create an ISO image, you can use mkisofs from cdrtools or other tools such as Debian's fork genisoimage. Most CD burning programs can burn a directory tree, or a pre-made image.

To access an ISO image, mount is with a or with a filesystem (FuseISO or fuseiso9660).