We know that Microsoft didn't provide offline ISO files of Windows 8.1 operating system for public download. If you use Windows 8 and want to upgrade to Windows 8.1, you'll need to download and install Windows 8.1 using Windows Store.
Some people want to perform a clean installation of Windows 8.1 operating system in their computers, but they can't because there is no official place to download Windows 8.1 setup ISO files. So first they'll need to install Windows 8 and then upgrade it to Windows 8.1 which would not be a clean installation of Windows 8.1.
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