> For the complete documentation index, see [llms.txt](https://docs.aurelia.io/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.aurelia.io/getting-to-know-aurelia/state-and-observation.md).

# State & observation

- [Understanding the binding system](https://docs.aurelia.io/getting-to-know-aurelia/state-and-observation/synchronous-binding-system.md): Learn how Aurelia's binding system balances synchronous notifications with async computed updates and how to manage state safely.
- [Observation](https://docs.aurelia.io/getting-to-know-aurelia/state-and-observation/observation.md): Observe changes in your applications.
- [Observing property changes with @observable](https://docs.aurelia.io/getting-to-know-aurelia/state-and-observation/observation/observing-property-changes-with-observable.md): Learn how to work with Aurelia's observable decorator to create reactive properties inside your component view models that have change callbacks.
- [Effect observation](https://docs.aurelia.io/getting-to-know-aurelia/state-and-observation/observation/effect-observation.md): React to derived state changes with Aurelia's effect observation APIs.
- [HTML observation](https://docs.aurelia.io/getting-to-know-aurelia/state-and-observation/observation/html-observation.md): Observe changes to native HTML element properties and attributes in Aurelia.
- [Using observerLocator](https://docs.aurelia.io/getting-to-know-aurelia/state-and-observation/observation/using-observerlocator.md): Tap into Aurelia's observerLocator to watch low-level property changes manually.
- [Watching data](https://docs.aurelia.io/getting-to-know-aurelia/state-and-observation/watching-data.md): Watch data changes reactively with the @watch decorator. Support for properties,  expressions, and computed values with automatic dependency tracking.


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