Run kubectl get pods in a Kubernetes cluster with Istio installed, and every application pod shows 2/2 containers. You deployed one container. The second is Envoy, and it now handles every byte of network traffic your application sends or receives. Envoy is an open-source, high-performance proxy for cloud-native systems. It handles networking tasks like routing, retries, timeouts, load balancing, encryption, and telemetry, replacing application-managed functions. By the end of this article, you’ll understand why Envoy exists, how its configuration works, and why Kubernetes tools such as Istio, Envoy Gateway, Contour, and Emissary build on it.