Basic Concepts

There are three concepts I need you to grasp before we begin: containers, images, and registries.

Containers

A container is what we eventually want to run and host in Docker. You can think of it as an isolated machine, or a virtual machine if you prefer.

From a conceptual point of view, a container runs inside the Docker host isolated from the other containers and even the host OS. It cannot see the other containers, physical storage, or get incoming connections unless you explicitly state that it can. It contains everything it needs to run: OS, packages, runtimes, files, environment variables, standard input, and output.

Your typical Docker server would look like this — a host for many containers: