The user guide is intended for anyone who wants to run programs and services on an existing Kubernetes cluster. Setup and administration of a Kubernetes cluster is described in the [Cluster Admin Guide](/docs/admin/). The [Developer Guide](https://github.com/kubernetes/kubernetes/tree/{{page.githubbranch}}/docs/devel) is for anyone wanting to either write code which directly accesses the Kubernetes API, or to contribute directly to the Kubernetes project.
Please ensure you have completed the [prerequisites for running examples from the user guide](/docs/user-guide/prereqs/).
: A label is a key/value pair that is attached to a resource, such as a pod, to convey a user-defined identifying attribute. Labels can be used to organize and to select subsets of resources.
: A replication controller ensures that a specified number of pod replicas are running at any one time. It both allows for easy scaling of replicated systems and handles re-creation of a pod when the machine it is on reboots or otherwise fails.
: A volume is a directory, possibly with some data in it, which is accessible to a Container as part of its filesystem. Kubernetes volumes build upon [Docker Volumes](https://docs.docker.com/userguide/dockervolumes/), adding provisioning of the volume directory and/or device.
: A namespace is like a prefix to the name of a resource. Namespaces help different projects, teams, or customers to share a cluster, such as by preventing name collisions between unrelated teams.
: A key/value pair that can hold larger (compared to a label), and possibly not human-readable, data, intended to store non-identifying auxiliary data, especially data manipulated by tools and system extensions. Efficient filtering by annotation values is not supported.
