A disk image is a file that contains the data and the same file structure as a physical disk or disk volume. As the image of a disk represents an exact copy of its physical sibling, disk images are used for various purposes, such as disk cloning (also known as disk imaging) and for backup. They are also used extensively in virtualization.

Disk imaging or disk cloning is the process of making a copy of a physical drive to a file (a disk image), and then using a disk image to create new disk images or physical drives, usually for the purpose of creating new physical or virtual computers. This enables the automation of computer deployments and saves significant amounts of time. The disk cloning process does not necessarily have to involve the disk image file, because cloning can be performed directly from disk to disk, but having an image has numerous advantages.

Windows uses its own image format, the Windows Imaging File Format (or WIM), which was introduced in Windows Vista. WIM images are compressed (using LZX or XPRESS compression) or uncompressed files containing operating system files, drivers, and applications. Using image files has the following advantages:

• Update: When operating system updates become available, you can update the image directly instead of updating the physical machine and performing an image capture.
• Portable: A disk image is a file that you can copy to and from any medium, making distribution, archiving, and backup easier. The WIM file format and its efficient compression methods allow you to store multiple versions of an operating system in the same file. For example, an image can contain Windows 10 Professional, Windows 10 Enterprise, and Windows 10 Education editions in a single file, with a file size that is significantly smaller than the individual sizes of all the operating systems added together.
• Change: You are able to add or remove operating system roles, and install or uninstall features or applications as needed.
• Deploy: A number of different deployment technologies or methods can use image files to deploy operating systems, such as Windows Deployment Services (WDS), System Center Configuration Manager, and System Center Virtual Machine Manager. You can also use images to deploy operating systems, even from portable media or from a shared network folder.