Docker Isn't a VM. Here's What It Actually Is.

The Mental Model Installing mental model for docker. Everyone says Docker is a lightweight virtual machine. Every tutorial shows the same diagram. Hardware, hypervisor, guest OS on one side. Hardware, kernel, containers on the other. And that diagram is fine. But it's hiding something. Something that changes how you think about containers entirely. A container doesn't create a fake computer. It doesn't boot an operating system. There is no guest kernel. Watch what actually happens. To understand why this matters, let's look at what a VM actually does. A virtual machine creates a fake computer. Virtual CPU. Virtual RAM. Virtual disk. Virtual network card. The hypervisor manages this illusion, giving each VM its own isolated hardware. The guest OS has no idea. It boots up. Loads drivers. Runs its init system. A complete operating system, running inside another operating system. And here's the cost. A typical Linux VM image is hundreds of megabytes. The app running inside it might be fift