Services are the resources which help to load balance the traffic route to the pods. Services works when the mapping defined in the Selector of service and labels defined at the pod is same.
1) ClusterIP- This is a default one. This works within the cluster.
2) NodePort- This is the service exposed at the Node level. This can be accessed from outside the cluster
3) LoadBalancer- This service will be created by kubernetes in conjuction with underlying environment. It can be AWS or Azure. This service has to add all the nodes where balancing needs to be done.