Envoy is a modern, open-source proxy platform designed for large-scale distributed systems. Unlike traditional proxies (HAProxy, NGINX), Envoy is dynamic—it reloads configuration without restarting, supports advanced routing policies, and integrates deeply with service discovery (Kubernetes, Consul). Advanced practitioners use Envoy as the data plane in service meshes (Istio, Consul), implementing traffic shaping, security policies, and observability at the network level—without modifying application code.