When & Why does Windows automatically save the Registry

[HappyAndyK]

The Windows operating system automatically saves the registry, every time a system restore point is created - whether automatically or manually by you.

This is useful, because when you restore your computer to a prior point, the OS needs the old registry backup too, in order to create a working restored computer. It is not important to only restore the files, but equally, if not more, important to restore the backed up registry too. That is when and why Windows saves the Registry automatically.

A System Restore will affect your system files, programs and registry settings. It can also make changes to scripts, batch files, and other types of executable files on your Windows computer. So any changes which have been made to these files, will be reversed. System Restore will not affect your Documents folder or Personal files like photos, emails, etc, but you may find files on your desktop going missing. So you may want to move your personal documents from your desktop to a safe location before effecting a system Restore. There is a way to find out which programs, drivers, files will be affected after a System Restore.

[RolandJS]

"...System Restore will not affect your Documents folder or Personal files like photos, emails, etc, but you may find files on your desktop going missing..."
HappyAndyK

You've given excellent reasons for having an OS & programs partition and a data & pic & downloads partition, C & D drives respectively. A little more work up front just might make recovery[s] of saved image[s], whether OS or data, much less destructive and much less problematic.

[HappyAndyK]

^ That is what I always do. OS + Programs on C Drive and Data on D Drive. I even shift my personal Documents folder to D drive.