alt Hacker News> In most varieties of English, disk is the preferred spelling for magnetic media (hence floppy disk, hard disk, disk drive), whereas disc is preferred for optical media (hence compact disc, digital versatile disc, optical disc).
> For all other uses, disk is preferred in American English and acceptable in Canadian English, and disc otherwise.
Also, disk is also used in "diskette", whereas disc stands alone. So as magnetic disks shrank and were called disketts on and off, they kept that spelling. Optical discs never really shrank over the years, never being called discettes.