High Quality Content by WIKIPEDIA articles! An ISO image (International Organization for Standardization) is an archive file (also known as a disc image) of an optical disc, composed of the data contents of every written sector of an optical disc, including the optical disc file system. ISO images can be created from optical discs or from a collection of files by image creation software; images can be used to write optical discs. Software distributed on bootable discs is often available for download in ISO image format, and used to write a CD or DVD. ISO image files often have a file extension of .iso. The name ISO is taken from the ISO 9660 file system used with CD-ROM media, but what is known as an ISO image might also contain a UDF (ISO/IEC 13346) file system or a DVD or Blu-ray Disc (BD) image.