ISO

Wikipedia has an article on:

ISO

ISO stands for the International Organization for Standardization. Its name, however, is often used as short-hand for its most used standards:

ISO 9660 

Filesystem used on CDs and DVDs.

ISO 900x 

Family of work management standards.

ISO images can easily be mounted in linux, to do so, do:

mount -o loop isoimage.iso /mnt/mountingpoint/

The image will now be mounted read-only. To unmount it, simply do:

umount /mnt/mountingpoint/

For additional information, please see Wikipedia's List of ISO Standards.