"FROM node:20-alpine"
We've all seen a line similar to that at the start of a Dockerfile. But what does that mean? Why FROM that one? Why FROM anything? What do we gain or lose by using that base image? And what ends up inside the final image we create? Other than the stuff we put in it, what else is in there?

Let's try to answer these questions with a mix of slides and demos. We'll go over the basics of what makes a docker image an image. Spend time dissecting an existing one. And even make our own from scratch. By the end of the session, we should have a better understanding of what an image is, and why it exists that way.