Microsoft has provided a secure sign-in system whereby you can sign into Windows 8 using your online Microsoft Account which is the new name for Windows Live ID, instead of creating a local user account.
The advantage of using your online Microsoft Account to sign into Windows 8 is when you are working across multiple computers that are connected to the same Microsoft Account, your various Windows settings, themes, passwords and app purchases will automatically sync* across all those computers.
Moreover, from the security point of view, when someone logs into a new Windows 8 computer using your Microsoft Account, the system will send you an instant email notification to confirm the same. You can easily disable that connection by following a link available in the same email message.
However, you can’t have a password of more than 15 characters.