What is Docker Images and Exaplin in 10 bullet lines?

Docker image is a collection of files systems.
It will have a ROOT FS, USR FS, APP FS.
ONE Copy of Docker image get attached to each Container
From one Image – you can get multiple Container.
Docker uses storage drivers to store image layers, and to store data in the writable layer of a container.
Docker image file systems strcutured in a layerd way.
All layers in a docker image is Read only.
All layers in an image is merged to one layer while creating the container. ( Union Mount)
Layer 0 have the root filesystem
Each layer in image will have 40 character length UUID generated by SHA 256 algorithm.