Biometric devices have been around for years, but many haven't delivered ironclad security. Many fingerprint readers, for instance, could be fooled by fake fingerprints, including those lifted via the infamous Gummy Bear hack. The technology's improving, however, and today's fingerprint readers use liveliness detection to check temperature, pulse, blood pressure, pores, perspiration and other traits of a living, breathing human. (So that gruesome, chopping-off-the-finger trick popular in movies probably won't work.)
What's this got to do with Windows 8.1? Well, the new OS will have improved biometric capabilities, including a common fingerprint login for different kinds of readers, including newer touch-based and older swipe-based models. You also can enable biometric authentication at various entry points, including Windows sign-in, remote access and User Access Control.