Disk image (ISO) binary file extensions

Generally speaking, a disk image file format contains the complete structure and content which represents a data storage medium or device (such as a hard drive, floppy disk, CD, or DVD) in a single file. A disk image is complete sector-by-sector copy of the source medium designed for perfect replication of the structure and content of the storage device. Historically, the first disk image file types were created to act as floppy disk backup, however, this practice extended to other types of media as they appeared.

Some of these formats may be compressed to reduce their file size, or even encrypted so they can be only used with proper credentials. Additionally, some metadata may also be saved in separate meta files so a whole "disk image bundle" is compromised of several files for maximum replication.

Some of the most common and widespread disk image include:

ISO - ISO binary image file - Binary image of CD/DVD in ISO 9660 standard, which defines a file system for CD-ROM media
BIN - Binary disk image file - Binary file is often used as CD/DVD backup image files, file format is very similar to ISO
DMG - Apple disk image file - Common format on Macs, used mainly to install new apps but can also act as CD/DVD backup
NRG - Nero or Nero Burning ROM image file - Used by NERO burning and multimedia suite and nrg file format uses a variation of the Interchange File Format (IFF) different from ISO
MDF - Alcohol 120% disc image - very often used format, file originally created in Alcohol 120%
UIF - Universal Image Format - developed and used by MagicISO, compression image file format for CD/DVD backup
ISZ - UltraISO Image Format - developed by EZB Systems, compressed CD/DVD image that can be also password protected
DAA - PowerISO Direct-Access-Archive - DAA CD/DVD image with supports for many special features including compression, password protection and multiple volumes splitting