San Antonio Disk Imaging
A disk image is a single file that contains the entire contents of a storage medium such as a hard Drive, CD/DVD, or Digital Storage Medium. Along with the contents, a disk image also contains information regarding the actual structure of the source medium.
There are many different file types associated with disk images and they are usually dependent upon the software package that created the image. However, for optical devices (CDs/DVDs) there is an open standard; ISO 9660 CDFS (Compact Disk File System).