How do you implement Docker container communication and service discovery?

Docker container communication methods: 1) Same host communication: Default bridge network allows containers to communicate by IP, Custom bridge networks enable communication by container name, Example: docker network create mynet, docker run --network=mynet --name web nginx, docker run --network=mynet --name app myapp (app can reach web by name), 2) Multi-host communication: Overlay networks in Docker Swarm, Example: docker network create --driver overlay myoverlay, 3) Service discovery: Docker Swarm built-in service discovery, Containers can reach services by service name, Load balancing across service replicas, 4) External service discovery: Consul, etcd, or cloud-native solutions, 5) Port publishing: docker run -p 8080:80 nginx (host port 8080 -> container port 80), 6) Environment variables: Pass service endpoints as env vars, 7) Volume sharing: Shared volumes for file-based communication. Best practices: Use custom networks for isolation, Implement health checks, Use service names instead of IPs, Monitor network performance.