For advanced users: gives you full control.
Microsoft replaced it with the (a UWP app) starting with Windows 8 and 10. However, the old Windows Photo Viewer (from Windows 7 and 8) still exists in the system files of Windows 10 — it's just not set as the default image viewer. windows photo viewer download for windows 10
[HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts.gif\UserChoice] "Progid"="Applications\photoviewer.dll" For advanced users: gives you full control