Ever wonder how Linux-based images can run on your Windows machine, even though the OS dependencies are Linux, and by container architecture, a Linux-based image should run on a Linux host to share the OS with similar images?

The “Runs Everywhere” Promise

Docker says:

Build once. Run anywhere.

And it works.

You pull a Linux image on your Windows machine,

docker run nginx

and the thing just runs.

But there is a quiet detail nobody talks about.

Linux Containers Need a Linux Kernel

Linux containers depend on Linux kernel features like cgroups and namespaces to work.

So they need a Linux kernel to run.

Not prefer.

Need.

That means Docker’s promise is really:

Runs everywhere a Linux kernel is available.

On a Linux host, your container talks directly to the kernel.

Zero tricks.

On Windows?

There is no Linux kernel.

So Docker has to bring one.

What Docker Actually Does on Windows

Docker uses a lightweight Linux VM through WSL 2 (or LinuxKit on older systems).

Unlike traditional virtual machines, this VM is highly optimized, so the overhead is minimal.

It also bridges:

Networking
File sharing
Resource management

so everything feels native.

Where Is Your Container Actually Running?

Your container is not running on Windows.

It is running:

Inside a Linux VM that runs on Windows.

Windows
│
└── WSL 2 / Linux VM
      │
      ├── Linux Kernel
      ├── Docker Engine
      └── Containers

The VM provides the Linux kernel.

The container borrows from it.

Windows is simply the host.

What About Windows Containers?

Windows containers are different.

They use the Windows kernel directly, so no Linux VM is needed.

The downside is that they only run on Windows.

Almost every image you’ll pull—nginx, postgres, redis, node—is Linux-based.

So 99% of the time, the Linux VM is doing the real work.

TL;DR

Docker Desktop doesn’t magically make Windows understand Linux containers.

It quietly starts a lightweight Linux VM, and that’s where your Linux containers are actually running.