What is used as a substitute for an actual disk, allowing software to run without loading a CD or DVD?

An ISO file serves as a digital representation of an entire disk, encapsulating the data and file structure of a CD, DVD, or other media into a single file. This allows users to run software that would typically require the physical media without needing to have the disk inserted into the drive. By mounting the ISO file using various software tools, the operating system interprets it as if it were an actual disk, allowing programs to access the contained data seamlessly.

In contrast, a virtual disk image is a broader term that may refer to various types of virtualized storage formats beyond just ISO files. A system image is typically used for backups and does not serve the same purpose as an ISO for software access. A disk clone involves making an exact copy of a disk, usually for recovery or migration purposes, rather than running software. Hence, an ISO file is the most accurate choice for this scenario.