A pod is the smallest deployable unit in Kubernetes. It can contain one or more containers. Most of the time, we just need one container per pod. In some special cases, more than one container is included in the same pod, such as sidecar containers (http://blog.kubernetes.io/2015/06/the-distributed-system-toolkit-patterns.html). Containers in the same pod run in a shared context, on the same node, sharing the network namespace and shared volumes. Pods are also designed as mortal. When a pod dies for some reason, for example, if it's killed by Kubernetes controller if resources are lacking, it won't recover by itself. Instead, Kubernetes uses controllers to create and manage the desired state of pods for us.
We can use kubectl explain ...
