Docker & Containers: Ground UP

If you've ever heard "works on my machine" — containers are the permanent fix to that problem. TL;DR A container bundles your app + libraries + minimal OS into a portable, isolated unit Containers share the host kernel — making them ~100× lighter than VMs Docker is the toolchain that builds, runs, and distributes containers The lifecycle is three commands: docker build → docker run → docker push DockerHub is the default public registry for sharing images What Is a Container? A container is a self-contained, portable unit of software. It bundles together: Your application code All required libraries and dependencies The minimum system dependencies needed to run Everything is packaged so the application runs identically regardless of the underlying environment — your laptop, a CI server, or a cloud VM in us-east-1. Simple Mental Model: Think of a container like a shipping container on a cargo ship. The contents are standardized and isolated. The ship (host OS) doesn't care what's inside