Service in Kubernetes is an abstraction layer for routing traffic to a logical set of pods. With service, we don't need to trace the IP address of each pod. Service usually uses label selector to select the pods that it needs to route to (in some cases service is created without selector in purpose). The service abstraction is powerful. It enables the decoupling and makes communication between micro-services possible. Currently Kubernetes service supports TCP and UDP.
Service doesn't care how we create the pod. Just like ReplicationController, it only cares that the pods match its label selectors, so the pods could belong to different ReplicationControllers. The following is an illustration:
Service maps pods via label selector ...
