What is docker image?

Docker image is template used to build the docker containers
Docker image contains application code, tools, dependencies and other files needed to make an application run
Docker images are store in docker registry
Docker images have multiple layers(base image, parent image, Layers), each one originates from the previous layer but is different from it
The layered file systems are identified using UUID which are created using SHA256 algorithm.
When we create a container – all layers are merged into 1 layer and that get mounted to container.
Docker merged directory is created when docker container process is started and it is removed when the container is stopped.