What is a Pod, and why is it the unit of scheduling rather than a single container?

A Pod is one or more containers that share a network namespace (same IP, can reach each other via localhost) and can share storage volumes, scheduled together onto the same node as an atomic unit. Multi-container Pods support sidecar patterns (e.g., a main application container plus a log-shipping or service-mesh proxy sidecar) that need tight co-location and shared networking, which is why Kubernetes schedules at the Pod level rather than scheduling individual containers independently.