The installation of Windows, Linux, or Mac operating system has been automated and foolproof for a long time, with no technical difficulty. But if you want to install and use multiple systems at the same time, whether it's a combination of multiple different versions of Windows or Windows + Linux + Mac (each has a different boot method), the hardest part is figuring out their installation order and adjusting the boot menu. This can be cumbersome and experience required even for advanced computer users.

Assume confronted the following situations: you want to reinstall Windows OS, but your CD/DVD-ROM is broken; or there is not a CD/DVD-ROM in your PC at all; or maybe you even don't have a Windows setup disk. So how to install Windows now? Can't you finish that without so many restrictions?