An ISO, typically shorthand for ISO image, is an image of the contents of a CD or DVD disc.
ISO files are convenient ways to distribute CD and DVD images for download, as they contain every sector that would be present on the original disc, including the boot sectors. When used to distribute software, such as operating system images, the result is that once the ISO image is actually burned to the corresponding media, it is a bootable disc from which that operating system can be installed.
ISO files are used to distribute more than operating systems, however, and are a common way to distribute anything that would benefit from being provided as a CD or DVD image.
Technically, ISO files are simply archives or collections of files, much like .zip files, though ISOs are not compressed. As a result, their contents can also be examined and extracted using several common archiving tools, such as 7-zip.« Back to Glossary Index