Why do we add labels to pods?

Aneek Bera:
why do we add labels to pods?

Christopher Town:
Labels allow selectors to determine which pods to group (LoadBalance) behind a Service.

Mohamed Ayman:
One use case for selecting over labels is to constrain the set of nodes onto which a pod can schedule.

Label selectors can be used as a quick and easy way to debug pods.

Anand Karwa:
This article should give you more details from what others have shared