A Microsoft account certainly has its share of benefits for some users in making their workflows more continuous. But for various reasons, including privacy concerns, others might have no need for a Microsoft tie-in, preferring instead to use a local account on the computer as Windows has done for ages.
So if you'd rather not opt-in to Microsoft's services, here's how to use Windows 10 with a local account.
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How to Use Windows 10 Without a Microsoft Account « Windows Tips