# Head node

The machine in a cluster that coordinates work: it schedules tasks onto compute nodes and tracks their results.

Source: https://university.eugo.io/glossary/head-node

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It schedules rather than computes. Results return through it, which is why a single enormous return value can make the head node the bottleneck even when the compute nodes are idle.

## Related terms

- [Cluster](https://university.eugo.io/glossary/cluster) — A set of machines, one head node and one or more compute nodes, launched together to run distributed work.
- [Compute node](https://university.eugo.io/glossary/compute-node) — A machine in a cluster that executes tasks. Compute nodes do the work; the head node coordinates it.
- [Scheduler](https://university.eugo.io/glossary/scheduler) — The component on the head node that decides which compute node runs each task, honoring the resources that task requested.