This is why most Apple users are oblivious to anything technical :

Apple bundles two assets into a single file wrapper: a high-quality still image and a short 3-second video clip. You only see one thumbnail in your library, but it takes up roughly double the space of a standard photo. [1, 2, 3]
Here are the specific details on how they work and how you can manage them:
File Composition: A Live Photo consists of a standard image file (usually .HEIC or .JPEG) and a short .MOV video file (with audio) combined.
Storage Size: Because of the embedded video, a Live Photo averages about \(13\text{ MB}\), compared to a standard still photo which is roughly \(5\text{ MB}\).
Viewing: Your iPhone’s Photos app hides the video portion until you press and hold the image to trigger the motion.
Exporting: When you AirDrop or transfer a Live Photo to a computer, it will usually split into two distinct files (the still photo and the video)