Docker 101
In this post, I'll explain what Docker is and why every developer should have it in their toolkit.
What is Docker?
Docker is OS-level virtualization that lets you run multiple software packages in isolated environments called containers — without the overhead of full virtual machines.
Think of it this way: instead of installing every dependency directly on your machine (and praying nothing conflicts), Docker lets each project live in its own little box with exactly the dependencies it needs.
Why Docker?
- No more "works on my machine" — containers run the same everywhere
- Easy dependency management — each container has its own isolated environment
- Quick deployment — ship containers instead of configuring servers
- Testing — spin up and tear down environments in seconds
Core Concepts
Docker Image
A blueprint file that contains everything needed to run your application — OS, dependencies, code, configuration.
Container
A running instance of an image. You can have multiple containers from the same image.
Layers
Images are built in layers, stacked on top of each other. This makes them efficient to store and transfer.
DockerHub
A public repository where you can find and share Docker images. Think of it as GitHub for containers.
Containerization
The process of bundling your application and all its dependencies into a container.
Getting Started
Install Docker
Head to docker.com and download Docker Desktop for your OS.
Essential Commands
# Pull an image from DockerHub
docker pull ubuntu
# Run a container interactively
docker run -it ubuntu bash
# List running containers
docker ps
# List all containers (including stopped)
docker ps -a
# Stop a container
docker stop <container_id>
# Remove a container
docker rm <container_id>
What's Next?
Once you're comfortable with the basics, explore Dockerfiles (building custom images), Docker Compose (multi-container applications), and container orchestration with Kubernetes.
Containerization is becoming an essential skill. The sooner you start, the better.