One can loopback mount a file containing an entire filesystem, notably a CD ISO image or a floppy disc image, under many Unix-like operating systems such as Linux and FreeBSD. This makes the files within said filesystem accessible on some mount point.

After doing so, the mounted files can be accessed with normal tools such as vi or GIMP, which need not be aware of how to read ISO images and such. One can also run mkfs commands to create an image file without needing the media the image will eventually be written to.

This feature is not available on Microsoft Windows.