* [kubelet](/docs/reference/command-line-tools-reference/kubelet/) - The primary *node agent* that runs on each node. The kubelet takes a set of PodSpecs and ensures that the described containers are running and healthy.
* [kube-apiserver](/docs/reference/command-line-tools-reference/kube-apiserver/) - REST API that validates and configures data for API objects such as pods, services, replication controllers.
* [kube-controller-manager](/docs/reference/command-line-tools-reference/kube-controller-manager/) - Daemon that embeds the core control loops shipped with Kubernetes.
* [kube-proxy](/docs/reference/command-line-tools-reference/kube-proxy/) - Can do simple TCP/UDP stream forwarding or round-robin TCP/UDP forwarding across a set of back-ends.
* [kube-scheduler](/docs/reference/command-line-tools-reference/kube-scheduler/) - Scheduler that manages availability, performance, and capacity.
An archive of the design docs for Kubernetes functionality. Good starting points are [Kubernetes Architecture](https://git.k8s.io/community/contributors/design-proposals/architecture/architecture.md) and [Kubernetes Design Overview](https://git.k8s.io/community/contributors/design-proposals).