To use Windows 8 you must have an account to log in with. There are 3 types of accounts on Windows 8.
- Local Accounts – These are local accounts only accessible on the local device.
- Domain Accounts – These are accounts created and controlled by Active Directory.
- Microsoft Accounts – Previously known as Windows Live ID. These accounts sync your settings with any machine you log into.
For further details on Microsoft Accounts you will find this post interesting – http://blogs.msdn.com/b/b8/archive/2011/09/26/signing-in-to-windows-8-with-a-windows-live-id.aspx