When is it necessary to bind a port on your host to a port on a container?

Binding a port on the host to a port on a container is essential when the container is running a network service that needs to be accessed from outside the container, specifically from the host machine or other devices on the network. This setup allows external users or applications to communicate with the service running inside the container.

For instance, if a container is running a web server on port 80 and you bind the container's port 80 to the host's port 8080, any requests sent to http://<host-ip>:8080 will be directed to the web server inside the container, thus making the service accessible. This binding establishes a clear pathway for network traffic, enabling effective interaction with the containerized application.

While saving data from a container, accessing external networks, or using services from within the container are important aspects of container management, they do not specifically require port binding for access. Port binding is crucial only when services need to be exposed externally.