> 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. --- # Agent Instructions This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com. ## Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation by asking a question. Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters: ``` GET https://docs.aurelia.io/getting-to-know-aurelia/state-and-observation.md?ask=&goal= ``` `ask` is the immediate question: it should be specific, self-contained, and written in natural language. `goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.