Apple introduced Animoji alongside the iPhone X in 2017. Launched initially with 12 different characters: Monkey, Robot, Cat, Dog, Alien, Fox, Poop, Pig, Panda, Rabbit, Chicken, and Unicorn, with each significant iOS upgrade Apple has added new Animoji to the line-up, with a total of 24 characters now available for users of the iPhone X, iPhone XS, iPhone XS Max, iPhone XR and Face ID-equipped iPad Pro models.
Animoji | Apple.com
Animoji works by analyzing more than 50 muscle movements in different areas of a users face with the help of Apple’s TrueDepth camera system on compatible devices, detecting movement of the eyebrows, cheeks, chin, eyes, jaw, lips, eyes, tongue, and mouth.
Facial movements made by a user are translated to the Animoji characters, making them reflect your expression and emotion. Users can choose to send a still sticker image of their character or record a video to be shared in the Messages app. Characters can also be overlapped and used instead of a users own face when making a FaceTime call.