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When a container starts, Docker takes an image and creates an isolated process from it. The sequence of steps at the **junior** level looks like this:

### **1. Docker takes the image**

An image is a template (layers with a file system and configuration). It is the foundation of the future container.

### **2. A writable layer is created**

On top of the image layers, Docker adds a **changeable layer**, where all the container's changes (logs, temporary files, and so on) will go.

### **3. The container gets isolated resources**

Docker configures namespaces and cgroups so that the container:

- sees **only its own processes**,
- has **its own file system**,
- has **its own network environment**,
- can use **limited resources**.

### **4. The main process starts**

Docker runs the command specified in `CMD` or `ENTRYPOINT` in the image.
This process = "the container's life".

### **5. The container runs as long as the process lives**

If the process ends, the container stops automatically.

### **Summary in one phrase**

> When a Docker container starts, an isolated environment is created from the image, a writable layer is added on top, and the main process starts, on which the container's life depends.

If you want, I can break down the same chain at the **middle level** (with details about OverlayFS, the PID namespace, the network namespace, and so on).

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