https://www.cnbc.com/2017/11/01/apple-iphone-x-animoji-mimic-your-face.html

The iPhone X has a lot of new features you won't find in any other iPhone, and one of the most fun is called Animoji.

Animoji animated characters -- a rabbit, a monkey, a robot and more -- that come to life when you move your face. The new 3-D face sensors on the iPhone X, which are also used for Face ID payments and to unlock the phone, can recognize your face's movements. If you smile, an Animoji monkey on your screen will mimic that smile almost exactly. The mouth will move when you speak, and the character's brows will mimic your own.