Persisting data using volumes to keep it safe when containers are removed.
The filesystem of a Docker container is ephemeral. Any data written inside the container's writable layer is lost when the container is removed. This is problematic for any stateful application, such as a database, that needs to persist data. Docker's solution to this problem is volumes. A Docker volume is a mechanism for persisting data generated by and used by Docker containers. Volumes are managed by Docker itself and are stored in a dedicated area on the host filesystem (e.g., `/var/lib/docker/volumes/` on Linux). The key advantage of volumes is that their lifecycle is completely independent of the container's lifecycle. You can create, manage, and delete volumes separately. When you attach a volume to a container, a directory inside the container is mounted to the volume. The application inside the container reads and writes to this directory as if it were a normal part of its filesystem, but the data is actually being stored on the host in the managed volume. If you stop and remove the container, the volume and its data remain untouched. You can then attach this same volume to a new container, allowing it to access the previously saved data. This makes volumes the preferred method for persisting data in services like databases, message queues, or for sharing data between containers.