# Knowledge Check: Images and Containers

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**1. State the image/container distinction in one sentence.**

*Answer:* An image is a packaged, read-only artifact; a container is a running instance created
from an image — the same relationship as a program file and a running process of it.

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**2. You run `docker rm -f my-container`. Does this delete the image it was created from?**

*Answer:* No — removing a container never removes the image; they have independent lifecycles
and separate removal commands (`docker rm` vs. `docker rmi`).

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**3. What does the `latest` tag actually guarantee?**

*Answer:* Nothing enforced — it's just a conventional tag name, not automatically "the newest
version" in any technical sense. Relying on it in production is a common source of surprise.

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**4. What's a layer, and why does layer sharing matter practically?**

*Answer:* A layer is one recorded change in an image's build (installing something, copying
files, etc.). Layers are cached and shared between images that share a base — meaning pulling a
new image that shares layers with one you already have can be much faster than its total
reported size suggests.

## Instructor Notes

**Facilitation:** Question 2 directly reinforces the previous demo — worth confirming everyone
got it right before moving on.

**Approximate timing:** 5 minutes.