Microsoft announced new security features for Windows 10 back in March that would use biometrics to allow you to securely log into the upcoming operating system. The biometric features, called Windows Hello and Microsoft Passport, can use multiple biometrics to authenticate your identity for access to the system and the information on it.
These new features can use facial recognition, iris scanning and your fingerprint to identify you and grant access.
In the leaked Windows 10 Insider Preview, build 10125, the Windows Hello dialog has been added to the Settings>Accounts>Sign-in options page, while the camera hardware is not yet available for facial recognition and iris scanning, adding your fingerprint for logging into the OS is possible.
These images are from that process on build 10125 and the most recent official build 10122. Build 10122 does not feature the Windows Hello dialogs however, if your system recognizes a fingerprint scanner it will offer that as an option for sign-in. Unfortunately, that process failed for me due to an apparent policy restriction even though I do not have any implemented on my main desktop.
See my full review of this feature over at my Using Windows Hello and a fingerprint to log into Windows 10 post.