How does facial recognition work?

Facial recognition systems follow a series of steps. First, software detects a face in an image or video and aligns it. Next, a deep neural network analyses features such as the distance between the eyes, the shape of the cheekbones and the contour of the jaw, and converts them into a string of numbers called a faceprint. This faceprint is then compared with a database to find a match. Apple Face ID, introduced with the iPhone X in 2017, projects more than 30,000 invisible infrared dots to build a 3D map of the face, with Apple quoting a one in a million chance that a random person could unlock your phone.