A service mesh is an infrastructure layer for facilitating service-to-service communications, with Envoy often utilized as a data plane component within service meshes such as Istio and Kong's Kuma. Envoy configurations can be complex due to its support for dynamic configuration, load balancing, protocol support, retries, circuit breaking, and rate limiting. Core components of Envoy include listeners, filters, clusters, and routes. Listeners receive traffic, filters process it, clusters determine the traffic's destination, and routes are used for directing HTTP traffic based on higher-level application knowledge. The control plane of a service mesh integrates with systems like Kubernetes to gather service information, translating it into configurations for Envoy using xDS APIs, which manage the discovery of components such as listeners and clusters. The Aggregated Discovery Service (ADS) streamlines this process by delivering configuration data in one continuous stream. Practical applications of Envoy in a service mesh context can be seen in demonstrations using Kubernetes and Kuma, showcasing how service mesh policies are translated into Envoy configurations.