# Concepts

> These pages explain how Harn fits together. They do not replace the syntax reference or a task guide.

Website: https://harnlang.com/concepts/index.html

This page documents Harn, which is pre-1.0. Language, standard library, and CLI APIs may change. If the intended version is unclear, clarify before using this page.

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These pages explain how Harn fits together. They do not replace the syntax
reference or a task guide.

## Read first

| If you want to... | Read... |
|---|---|
| See how the main pieces fit together | [Mental model](./mental-model.md) |
| Choose between a call, loop, workflow, or worker | [Choosing an abstraction](./abstraction-ladder.md) |
| Find the exact meaning of a Harn term | [Glossary](./glossary.md) |
| Understand the Harn/host boundary | [Host boundary](../host-boundary.md) |
| Compare Harn terms with other agent tools | [Coming from elsewhere](./sota-comparison.md) |

## If you need to ship code

- [Getting started](../getting-started.md) — install Harn and run a first
  program.
- [Language basics](../language-basics.md) — learn the syntax.
- [LLM calls and agents](../llm-and-agents.md) — choose a model-backed API.
- [Common tasks](../common-tasks.md) — follow a focused implementation path.

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## Read next

- [Introduction](https://harnlang.com/introduction.md)
- [Mental model](https://harnlang.com/concepts/mental-model.md)