Smartphones are a useful technology. They have some secrets. One is on the new iPhone. It can measure someone's height. You point your camera at a person and an app gives you their height. The person must stand in front of the camera from head to toe. The new app could stop people arguing about who is the tallest.

The app is called Measure. It uses a special sensor and a technology called LiDAR. This is "light imaging, detection, and ranging". LiDAR is used to take digital photos of the Earth. It measures a person's height by bouncing light off them. When the light returns to the sensor, the app calculates the person's height.