To find out, I asked Luuk Spreeuwers, a researcher in biometrics and facial recognition at the University of Twente. How does facial recognition work? To understand how facial recognition works, Luuk first distinguishes between two methods: verification and identification. Your phone uses verification. The system already knows who you are supposed to be: the owner of the phone. Luckily, your phone doesn’t have to search through millions of faces to find yours. It only needs to determine whether the face in front of the camera matches that of the owner. To do this, the system compares features from the face in front of the camera with previously stored features from one specific person. Luuk calls this a 1:1 comparison. The result is either a match or a non-match. Identification works differently. In this case, the system doesn’t yet know who the person in front of the camera is and is trying to find out. It compares the features of one face with those of multiple people stored in its database. Luuk calls this a 1:N comparison. The system then looks for the best match or concludes that there is no match. So, the main difference lies in the question the system is trying to answer. Verification asks, ‘Are you this person?’, while identification asks, ‘Who are you?’ You can see a similar principle to verification at automated passport control. There, the system can compare features from a live camera image with features from the passport photo stored on the chip in your passport. But what does facial recognition actually look at? Your phone doesn’t simply look at your eye colour or the distance between your nose and mouth. Modern facial recognition systems use deep learning, a form of artificial intelligence, to extract distinctive features from a face. ‘These systems are