An ISO image is an informal term for a disk image of an ISO 9660 file system. More loosely, it refers to any optical disk image, even a Universal Disk Format image..

As is typical for disk images, in addition to the data Computer file that are contained in the ISO image, it also contains all the filesystem Metadata (booting code, structures, and attributes). All of this information is contained in a single file. These properties make it an attractive alternative to physical Data storage device for the distribution of Computer software which requires this additional information as it is simple to retrieve over the net.

Some of the common uses include the distribution of operating systems, such as Linux or Berkeley Software Distribution systems, and LiveCDs.

Most or generating new ones from existing files, or using them to create a copy on physical media.

Most operating systems (including Mac OS, Berkeley Software Distribution, Linux and Microsoft Windows, with third-party tools) allow these images to be mounted as if they were physical discs, making them somewhat useful as a universal archive format.

Console emulators, such as EPSXe, and many other emulators that read from CD, are able to run ISO/BIN (and other similar formats) instead of running directly from the CD drive. Better performance is achieved by running an ISO since there is no waiting for drive to be ready.

= CDs vs. disc images (from emulation point of view) =

== CD ==

Pros

- Low price

- Physically portable

- Extractable to ISO

Cons

- Susceptible to damage

- Slower performance

- Takes up physical space

== Disc image ==

Pros

- Free

- Electronically portable

- Can be reproduced in CD format

- Speed depends on hard drive

- Takes up no physical space

Cons

- May not run or install correctly unless written to a CD

- Susceptical to corruption

- Can be as large as 700 MB (or more if from DVD or other media)

=See also=