How is a service connected to a pod? In yaml, what fields need to match between service and pod?

When creating a Kubernetes service, I'm trying to understand what fields in the YAML service definition need to match to a PODs definition.

For example, given the service:

apiVersion: v1
kind: Service
metadata:
  name: nginx-service
spec:
  selector:
    app: nginx-selector
  ports:
    - protocol: TCP
      port: 80
      targetPort: 8080

What field in the Pod definition needs to say nginx-selector. I think it's the field I've labeled (metadata.labels.app = nginx-selector).

So given this Pod definition

apiVersion: v1
kind: Pod
metadata:
  name: myapp
  labels:
    app: nginx-selector
spec:
  containers:
    - name: myapp
      image: pats2265/myapp
      labels:
        app: does-this-matter
      ports:
        - containerPort: 8080

So many examples use names that are identical between several fields so I wanted a trivial example to spell it out.

This was a good diagram: Taken from https://matthewpalmer.net/kubernetes-app-developer/articles/service-kubernetes-example-tutorial.html

But it didn't show the corresponding Pod definition.

Searches came up with this question:

• How to communicate between pods in a service? - Which I think answers my question, so this can be marked as a duplicate but my question is more specific so I'd like to keep it to help others out.

You are right...its the label of pod which should match with selector defined in service. Check this link for more understanding- https://kubernetes.io/docs/concepts/services-networking/connect-applications-service/