Carmela writes in with a question after wiping a 2010 MacBook Pro and reinstalling macOS:
I wanted to restore it to factory settings, but while erasing the disk I erased not only “Macintosh HD” but the “Hitachi…” What have I done? I reinstalled the OS fine. Did I damage my system?
This highlights how well Apple typically hides some of the fussy details of an operating system from users, usually to the good: most of the time, we don’t need to know any low-level details in order to use a Mac. iOS obviously goes a few steps further, mostly preventing even advanced users from seeing much of what’s under the hood.
What Carmela is seeing is the difference between a drive and a partition. While this may be old hat for veteran users, it’s just jargon for those who have never had to format a drive before.
A drive is a physical thing, whether it’s a hard disk drive (HDD) or solid-state drive (SSD). It’s a physical medium that has a disk controller that mediates access to data stored on the disk, including carrying out and tracking the details of what bits are written where, and how to retrieve them later.