A container that runs the same everywhere

How a container differs from a virtual machine, what an image is, and how to live with docker run, ps, logs, exec.

How Docker builds an image, why the order of lines decides build speed, and which instruction to use when.

Where to keep data, how containers find each other by name, and what port publishing really does.

One file describes the whole stack, and a healthcheck makes sure the API starts after the database is ready.

Multi-stage builds, choosing a base image, a non-root user, .dockerignore and vulnerability scanning.