Historically, software was sold on several floppy disks and when buying a new piece of software the first task was to copy all the floppy disks onto the computer's hard disk, from where you could run programs without having to keep swapping floppy disks. Now that CD-Rom drives are so common (and CD-Rom discs are so cheap to make) many software distributors have switched to selling programs on CD-Rom discs instead of floppies.
