A Microsoft account is an email address and password that you use to sign in to Windows. It’s free and easy to set up, and you can do so with any email address you choose, or get a new email address.
For example, you can use an Outlook.com email address for your Microsoft account. If you don’t have an account you can visit https://outlook.com and register a new email address.
(Note: Even if you can use Gmail or Yahoo email address for a Microsoft Account, I would not recommend it as from my experience you eventually end with a conflict between Microsoft Services and Google or Yahoo services.)
When you sign in to your PC or device with a Microsoft account, you can get apps from the Windows Store, back up all your important data and files using free cloud storage, and keep all your favorite stuff—devices, photos, friends, games, settings, music, and so on—up to date and in sync.
You get 7GB of Microsoft Cloud Storage Free when you sign up for a Microsoft Account. You can store documents, pictures, music or videos on One Drive. The contents of your One Drive can be accessed on the Web at Outlook.com These folders are also available on your computer when you open the “THIS PC” in File Explorer.
You can also see the “About One Drive Page” at https://onedrive.live.com/about/en-us/