The notch made room for Face ID
Apple’s iPhone X design paired a nearly edge-to-edge display with a new face-recognition system. Face ID needed more than an ordinary selfie camera: its TrueDepth system combined a camera with infrared sensors and a dot projector, which mapped the user’s face to verify identity. Those parts needed physical space at the top of the phone, where a continuous screen would otherwise go.
The notch was the shape left around that hardware. It let the display extend upward on both sides of the sensor cluster instead of reserving a full-width strip of bezel. In other words, the cutout was not a component that Face ID itself required; it was a compromise between fitting the sensors and extending the screen.
A constraint, not the only possible design
There was no universal engineering law that required Apple to use a notch. A larger bezel could have housed the same hardware, but it would have reduced the display area. Moving or shrinking components would have required a different design, and Apple’s 2017 phone was built around putting Face ID sensors above the screen while keeping the front largely display.
That distinction explains why the notch was controversial: the hardware made a cutout useful within Apple’s chosen layout, but the particular choice to bring the screen around it was a design tradeoff. The result was more display across the phone’s top edge, interrupted exactly where the face-recognition system needed room.
