It won’t have a copy of every single wallpaper ever but it will have a reasonably long history of them. Windows 10 keeps a copy of every wallpaper that you use. If you move the files, and one of them is still in use, you will end up with a black wallpaper. You shouldn’t move any files from this folder unless you do not intend to use them. Inside this folder, you will see all your synced wallpapers. This will open File Explorer and you will see a ‘DesktopBackground’ folder. %localappdata%\microsoft\windows\themes\roamedthemefiles You can also enter it in the location bar in File Explorer. The quickest way to view all synced wallpapers on Windows 10 is to open the run box with the Win+R keyboard shortcut.