Windows 10 includes an option to Reset this PC which can be accessed in Settings → Update and Security → Recovery.
When you choose to reset, you're given some options:
The "Keep my files" option says it "keeps your personal files", but which files does it actually keep? Personal files could mean files in my Windows user folder, or it could just mean the Documents, Pictures, Music, and Videos folders, or it could mean everything that's not Windows.
Sometimes I need folders without spaces in the path, so I store (important) files directly in the C drive. Are these saved as "personal files"?
Although I have backups, I'd prefer not to have to use them.
For the purposes of Windows 10 reset, what are considered personal files?