Docker has become one of the most important tools in modern software development. This first part of the series explains the "why" before we touch any commands.
What Is a Container?
A container packages an application together with everything it needs to run — code, runtime, system tools and libraries — so it behaves the same way everywhere.
Containers vs Virtual Machines
Unlike a virtual machine, a container doesn't need its own full operating system. It shares the host OS kernel, which makes containers much lighter and faster to start.
Key Differences
- Containers start in milliseconds; VMs typically take longer.
- Containers share the host kernel; VMs run a full guest OS.
- Containers are typically measured in megabytes; VM images in gigabytes.
Why Docker Specifically?
Docker made containers accessible with a simple CLI, a huge image registry (Docker Hub), and tooling that just works across operating systems.
In the next part, we'll install Docker on Ubuntu 22.04 and run our first container.