Basics

• Containers run on top of Container Engine which runs on top of a Host OS
• A containers runs an image e.g. docker image
• An image consists of layers.Each layer is a read only image on top of other layer
• Docker container is running copy of Docker Image
• Other than static read only layers from the Image, a container has a Read Write layer file system layer
• Whatever happens at runtime is saved in this RW layer
• Container registry/Hub is a repository of Container Images. These can be either public or private
• Dockerfile contain definitions of Container Images