An .ISO is an exact image of a CD or DVD.
In the context of files and programs, an "image", whether an ISO, floppy, or other media image, is simply a file that can be used as a virtually identical copy of the original media. This file not only contains individual data files, but it also contains track and sector information and arranges all this information in a file system, just like disk media. Image files, unlike normal files, are usually not opened; rather, they are mounted.
An ISO image is simply a CD-ROM image saved in ISO-9660 format.
ISO images are mainly used as source files from which to create CDs. As an example, most distributions of Linux release ISO images of the installation CDs. These images are usually available from anonymous FTP servers (such as Indiana University's ftp.ussg.iu.edu server). Once you download the image, you can use CD burning software to recreate the physical CD-ROM install media.
Definition Source: http://kb.iu.edu/data/amxs.htmlSo, for example:
Here is a quick breakdown of how to copy a DVD image file to your blank DVD using Sonic CD/DVD burning software.
1) Insert your DVD
2) Start Sonic (This can be done by using the desktop shortcut; clicking on start > programs > sonic; or by clicking on the iso image itself).
3) Click copy (on the left side of program)
4) Select the Burn Image option (left side of program)
5) Browse to your image and select it
6) Press the big red "burn Image" button (right lower side of program). Wait about 10 minutes for your copy to complete. Remove DVD as use appropriately =D