Docker guide clarifies image vs container

Ryan Kikayi's June 1, 2026 dev.to post frames Docker images as immutable blueprints and containers as live houses built from those blueprints [DevTo]. The article lists the Docker commands that create each artifact—docker build or docker pull for images, docker run for containers—and shows how a single image can spawn unlimited containers. Docker's own documentation confirms that images are stored as read-only layers on disk, while a container adds a writable layer on top of those layers [Docker Docs]. This distinction has several implications. Debugging becomes deterministic because engineers can reproduce bugs by rerunning the exact same image. Storage costs stay predictable since each container adds only a thin writable layer, keeping the disk footprint of dozens of containers derived from the same image bounded [Docker Docs]. Security policies also stay enforceable because Docker's runtime enforces read-only access to the image layers, with any write operation landing in the container's writable layer, which can be discarded on stop [DevTo].