What is a Kubernetes Service Mesh (e.g., Istio)?

A Service Mesh is a dedicated infrastructure layer for facilitating service-to-service communications between microservices, using a sidecar proxy pattern.

Istio injects an Envoy proxy sidecar into every pod. These proxies manage all inbound and outbound network traffic. The mesh abstracts complex networking logic—like mutual TLS (mTLS) encryption, traffic routing, circuit breaking, retries, and distributed tracing—away from the application code.