What is Namespace (Linux)?

Linux namespaces are a kernel feature that partitions kernel resources so that one set of processes sees one set of resources while another set of processes sees a different set. Docker and Kubernetes use namespaces to isolate containers: PID namespace (isolated process IDs), NET namespace (isolated network stack), MNT namespace (isolated filesystem mounts), UTS (isolated hostname), IPC, and User namespaces. Namespaces + cgroups are the two core technologies behind containers.