Originally, personal computers only had a floppy disk drive, which got letter A, and later models could have two floppy drives, so A and B. When hard disk drives appeared they got assigned to letter C (and typically D for a secondary HDD). E then became customary for optical drives (CD-ROM, DVD-ROM etc.)
this
Nobody ever asks why it’s the C:\
Pour one out for A:\ and B:\
Originally, personal computers only had a floppy disk drive, which got letter A, and later models could have two floppy drives, so A and B. When hard disk drives appeared they got assigned to letter C (and typically D for a secondary HDD). E then became customary for optical drives (CD-ROM, DVD-ROM etc.)