> For the complete documentation index, see [llms.txt](https://docs.activejs.dev/activejs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.activejs.dev/activejs/fundamentals.md).

# Fundamentals

- [Units](https://docs.activejs.dev/activejs/fundamentals/units.md)
- [BoolUnit](https://docs.activejs.dev/activejs/fundamentals/units/boolunit.md)
- [NumUnit](https://docs.activejs.dev/activejs/fundamentals/units/numunit.md)
- [StringUnit](https://docs.activejs.dev/activejs/fundamentals/units/stringunit.md)
- [DictUnit](https://docs.activejs.dev/activejs/fundamentals/units/dictunit.md)
- [ListUnit](https://docs.activejs.dev/activejs/fundamentals/units/listunit.md)
- [GenericUnit](https://docs.activejs.dev/activejs/fundamentals/units/genericunit.md)
- [Systems](https://docs.activejs.dev/activejs/fundamentals/systems.md)
- [AsyncSystem](https://docs.activejs.dev/activejs/fundamentals/systems/asyncsystem.md)
- [Custom AsyncSystem](https://docs.activejs.dev/activejs/fundamentals/systems/custom-asyncsystem.md)
- [Action](https://docs.activejs.dev/activejs/fundamentals/action.md)
- [Cluster](https://docs.activejs.dev/activejs/fundamentals/cluster.md)