What is this Folder: Windows.old after Windows 10 upgrade?

As stayed in the title. I have upgraded my PCs and Laptops from initially Win 7 to Win 10 without problems for a change. In fact I fairly like it and prepared to keep it! However I found this /Windows.old folder in each of my upgraded PC or laptop, in additional to /windows normally. Because all my Windows 10 upgrades are LESS than 30 days old at the moment, is it the special folders which keep all my previous Windows 7 system and related files so that in case I wanted to revert back to Windows 7 after upgrading to Windows 10 that I may do so?? Would therefore mean this "windows.old" folders/Links will be auto-deleted from my PCs/laptops after 30 days of Windows 10 upgrades??

The reason I'm asking this is I start doing Image Backups for each of my PC/laptop, this /Windows.old tends to consume a lot of data and as such I would like to delete it myself prior to the Image Backup. But what about the associated LINKs in Windows 10??

Yes, it's the old version of Windows. I think with Win 10 it will auto delete after the 30 days - other versions of Windows it would stay forever unless you chose to delete it.

If you aren't going to downgrade before the 30 days is up you should be able to delete it.

Thank you for your reply! I may delete this /Windows.old folder early but I am a bit worry I may "screw-up" the associated LINK/s such as selecting to go back to my previous Win 7 etc. It may be less concerning if I waite for over 30 days when this OLD Folder been auto-delete by Windows.

Disk cleanup >> clean up system files >> check "previous installations."

Yes, it is the back-up of your previous version of Windows in case you want to revert back to it. it won't be deleted auto by Windows but when you do a Disk Clean-up incl. System Files you may choose to remove it. You will be given a warning that if you do you will then never be able to go back to the previous version of Windows.

Thank you for your reply! According to your "Quote": it won't be deleted auto by Windows but when you do a Disk Clean-up".
This "Disk Clean-up App" how do you invoke them in Windows 10 or Is it within the normal Windows' Accessories Menu??

Thanks

It should be among Windows Admin Tools but I structure my own menus so I might have moved it. In any case it is the program "%windir%\system32\cleanmgr.exe".

Just press the Start button and type: disk cleanup

Win 10 has a search bar within the task bar so you don't need to even press start these days - just put the cursor in the search box and type (or if supported use speech recognition in Cortana - but personally I would type it).

Certainly better than navigating menus