What is a docker image ?

Docker Image is a software package that contains everything to run an application.

Docker image has multiple filesystems called Layers .

Layers are stacked one over the other.

Every layer has a parent layer.

First layer is known as the base image .

Every layer has a merged & diff directory.

Merge directory is something that is attached for the user .

Every layer has a different SHA value .

If you stop the container the merge directory goes away.