Explain how network interaction occurs inside a Docker container and how it connects to external networks.

In a Docker container, network interaction is organized through virtual networks that Docker creates and manages.

Key points:

• Each container gets a virtual network interface (usually eth0) with an IP address within the Docker network.
• By default, Docker creates a bridge network to which containers are connected.
• Containers within the same network can communicate with each other via IP or container name.
• To access external networks (the internet), the container uses NAT through the host machine.
• Custom networks (bridge, overlay) can be created for isolation and configuration.
• Container ports can be forwarded to the host so that external applications can access services inside the container.

Example of running a container with port forwarding:

docker run -d -p 8080:80 nginx

Here, port 80 inside the container is accessible on port 8080 of the host.