Also see ghost.
Ghost imaging is the copying of the contents of a computer's hard disk into a single compressed file or set of files (referred to as an image) so that the contents of the hard disk, including configuration information and applications, can be copied to the hard disk of other computers or onto an optical disc for temporary storage.
An example of ghost imaging software is Norton Ghost, a product from Symantec. Using this product, you can clone (copy) the entire contents of a hard disk to a portable medium such as a writeable CD or to a server. The portable image can then be used to set up each hard disk in other computers, automatically formatting and partitioning each target disk. Ghost imaging is useful where one system is to be replicated on a number of computers in a classroom or for a team of notebook computer users who all need the same system and applications. On personal computers, ghost imaging is used to back up everything on the hard disk, often while reinstalling an operating system.