These folders can be used as backup to recover any files or settings that may need after update/upgrade to the new system. When you update your system from Windows 8 to 8.1, or upgrade from Windows 8.1 to 10, it keeps your previous Windows system files in “Windows.old” folder and the installation files of the new system in “$Windows.BT” folder. I use the tool on a routine basis and simply made a shortcut and drug it above my START button on both my desktop running Windows 7 Pro and my laptop with Windows 8.1 Pro. Dennis, A shorter way to get to the tool without any typing is: Programs, Accessories, System Tools, Disk Cleanup. Those old files then stay on your PC for a month (unless you delete. When you upgrade to Windows 10 from Windows 7 or Windows 8, your existing Windows installation is saved, rather than deleted.
