Disk image is a file which stores entire content & structure of a disk or a volume. This disk could be hard disk, USB flash drive, tape drive or optical media such as CD, DVD, and Blu-Ray disk. Besides, it uses various file extensions that includes .ISO, .DMG, .BIN, .VHD etc.
The file belongs to the category of Disk Image Files.
Disk Image can be opened in various software depend on their file format
"I found this to be of great help while learning about the concept of disk image" Wilbur Smith | Alaska
"I think is the simplest way of describing about disk image without creating any further confusion." Ruth Ramirez | Spain