Apple's new Face ID system uses a sensing strategy that dates back decades

The kind of facial recognition that Apple

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is doing is different from what, say, Facebook does when it identifies a photo of you and suggests a tag—that’s taking place in the two-dimensional landscape of a photograph, while the latest iPhone is considering the three dimensions of someone’s face and using it as a biometric indicator to unlock (or not) their phone.

Alas, you’ll need to pony up the $999 for an iPhone X, as this feature only works on the company’s new flagship smartphone. Among the sensors that comprise what the company calls the TrueDepth camera system that enable Face ID are an infrared camera and a dot projector. The latter of those projects a pattern of more than 30,000 infrared dots on the user’s face when they want to unlock their phone, according to Phil Schiller, a senior vice president at Apple who described the technology yesterday.