Our faces each have unique bone, capillary and muscular construction, in addition to physical characteristics and pigments that are specific to each one of us.

Even identical twins aren’t truly carbon copies of each other—they have thousands of tiny, potentially even imperceptible differences. Just like we each have unique fingerprints, we also have unique faceprints.

When a recognition system scans a human face, it can be used to identify who the person is, based on their biometric features.

Snap’s famous selfie filters use faceprints to map digital overlays and alter them in real time. China’s Alipay uses faceprints to authenticate people’s identities as they make purchases. Facebook uses the technology to automatically tag people in the photos uploaded. Shanghai-based Fudan University and Changchun Institute of Optics, Fine Mechanics and Physics (part of the Chinese Academy of Sciences) in Changchun developed a 500-megapixel facial recognition camera that is able to capture “thousands of faces at a stadium in perfect detail and generate their facial data for the cloud while locating a particular target in an instant.”

In practice, this means that a stadium can be scanned and, within seconds, produce a high-resolution image of every single face for recognition algorithms.

Researchers in Japan and China are working on representation models that require only a portion of one’s face, even in low light, to accurately predict their identity—even as they change their hairstyles, get plastic surgery or grow a beard. Legal challenges in 2019 resulted in some U.S. cities barring city departments from using facial recognition technology without first going through approved procedures.

Individual cities, counties and states now have different regulations stipulating who can use faceprints and under what circumstances.