Namespaces
Virtual cluster inside a K8 cluster.
Group virtual cluster by resource grouping, example: monitoring namespace, logging namespace, etc.
Another usecase is if multiple teams are deploying with same deployment names. This will override existing deployment on a single namespace.
Can be used for Blue/Green deployments as well. These can use common resource. You can have a single monitoring namespace for blue and green namespaces.
Some resources cannot be shared across namespaces, such as ConfigMap and secrets. Service can be shared across namespaces.
Volumes and nodes cannot be namespaced. They just live globally in the cluster.