The next release of Windows 10 supports Microsoft Passwordless Accounts. Microsoft simply sends a code to your phone number when you sign in. This is all part of Microsoft's stated goal: "A world without passwords".
This feature is now available in Insider Build 1
Here's how it works: You can now create a Microsoft account without a password. Instead, just enter your phone number. When you sign in to Windows 10 with this phone number, Microsoft sends you a code that you enter on the login screen. Then you can use Windows Hello to set up a PIN, fingerprint, or face registration method. You never have to enter a password – your account does not even have a password! Also, you do not have to enter any code that is sent by text each time you log in. You just need to get a code on your phone when you log in to a new PC.
To use this feature on the latest insider builds in Windows, you need a Microsoft account without a password:
If you do not already have a password without a password, you can in a mobile app like Word on your iOS or Android device to try it out. Just go to Word and log in with your phone number by entering your phone number under "Register or register for free."
This latest release also provides an optimized PIN reset experience for Windows Hello and narrator enhancements.  CONNECTING TO: Next Windows 10 update will make your PC faster thanks to better corrections by the "Specter Specter"
Credit: KC Lemson / Microsoft, Microsoft