Container networking enables communication between containers, with external services, and across multiple hosts. In Docker, networking is implemented through pluggable drivers (bridge, overlay, host, macvlan, ipvlan, none), each serving different use cases from single-host isolation to multi-host orchestration. Kubernetes extends this with its own networking model requiring that all pods can communicate with each other without NAT, managed through CNI (Container Network Interface) plugins that provide the actual network implementation. Understanding container networking is essential because network isolation, DNS resolution, service discovery, and load balancing are fundamental to microservices architectures — without proper networking configuration, containers remain isolated islands unable to collaborate as distributed systems.