A VirtualService defines traffic routing rules for a service. Without one, Istio sends traffic round-robin to all pods behind a Kubernetes Service. With a VirtualService, you control how requests reach your workloads - split traffic by weight, match on headers, rewrite URLs, or route to specific versions. apiVersion: networking.istio.io/v1beta1 kind: VirtualService metadata: name: my-app spec: hosts: - my-app http: - route: - destination: host: my-app subset: v2