Dave has a questions about multiple operating systems on his PC. “Can a person use Win 10 and Linux on same machine? What about keeping Win7 amd/or 8.1.”
Just as with any other version of Windows, you could choose to run it in a dual-boot with Linux on one machine or as a virtual operating system inside Linux. I’ll warn you, it will be much slower.
You could also choose do dual boot Windows 10 with Windows 7 or Windows 8.1. But remember, in order to get Windows 10 for free, you have to upgrade from Windows 7 or 8. You’re swapping that Windows 7 or 8 license for your Windows 10 license. You’re not getting an extra one. So if you want to keep your current OS and also run Windows 10, you’ll have to pay for it.