In short, a container is a standardized unit of software that packages up code and all its dependencies so the application runs quickly and reliably from one computing environment to another.
Technically speaking, a container is just an isolated process running on a host machine.
Unlike a Virtual Machine (VM), which simulates an entire hardware stack — including a full Guest Operating System and Kernel — a container shares the host machine's kernel.
But why use containers instead of VMs?
- Lightweight: Containers don't need to boot a whole OS. They start in seconds.
- Efficiency: They use the host's CPU and RAM directly, without the "middleman" (Hypervisor) overhead.
- Portability: Since the container carries its own "world" (libraries and dependencies) inside its Namespaces, it runs the same way on your Mac, on a Linux server, or in the AWS Cloud.