The term "ISO file" refers to a single file which contains within it a file system conforming to the international ISO 9660 standard. The ISO 9660 standard defines the file structure to be used for CD-ROM media which ensures all CD-ROM drives conforming to the standard can read data discs regardless of the operating system of the computer.
An ISO is an archive of the contents of a CD or DVD that can be stored on a hard drive for later use. ISOs can either be generated from burning software for distribution or as an archive of the contents of a CD or DVD. In addition to storage for burning, ISO files can also be mounted onto the computer and act as virtual drives to be read or even added to. In this respect, the use of a CD/DVD drive can be entirely avoided.
ISO files are commonly refered to as "ISO images", "ISOs" or just generically under the term "image". The term image also encompasses other file formats such as MDF, CUE/BIN, IMG, DMG, or NRG. All of which were designed to perform the same function as ISO but to the needs of a particular application. For more information on each respectively, see Wikipedia.
An ISO file typically has the file extension .iso, but some operating systems such as MAC OS use the file extension .cdr.
Purpose of an ISO File
ISO files are ideal for distributing anything that would also be suitable for distribution on optical media. The main advantage of an ISO file is that it can be transferred over the network and the recipient can then 'burn' the ISO image to create their own CD. Through checksums, the file can also be guaranteed to be an exact copy of the data originally created.
Almost all Linux distributions are offered in ISO format for download.
Please see the page BurningIsoHowto for complete instructions on how to burn an ISO image onto a CD or DVD.
Create an ISO
For instructions on how to create ISOs from a CD or DVD, see CreateIsoFromCDorDVD.
For instructions on how to mount an ISO, see MountIso.
Advanced Image Management
For more advanced operations with images, including conversions between formats see ManageDiscImages.