If you want to use Apps, themes, games, movies and tv from the Microsoft Store, you need to have a Microsoft account login.
For example, to use Cortana with voice commands, you need a Microsoft account to download apps from the Microsoft Store. If you are using a Microsoft account, you can use everything related to Microsoft products.
If you are using Microsoft computer on one computer and you are logged in to the same account on the other device, you will be able to access settings, Themes, Apps, Mails, OneDrive, Xbox, Store, Movies from the first device.
If you want to use Windows update insider preview, you need to have a Microsoft account. Once you have Windows installed on your PC and logged in to your Microsoft account, you will be able to use all the settings you used before installing Windows. If you want to use Office 365, you need to activate it with a Microsoft account. If you are using a local account, if something goes wrong and your user profile is corrupted and you can no longer use it, you may have to back up your new user data.
To connect to a Microsoft account, select Accounts in Computer settings. You can login to your Microsoft account by selecting Email and accounts, clicking Add a microsoft account.
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