# State basics

## Overview

These concepts form the foundation of SwiftCrossUI's reactivity.

Use the ``State`` property wrapper to store state within your apps, scenes,
and views. State generally trickles down through your view hierarchies. Variables
without the ``State`` annotation aren't reactive.

If you want to persist a small amount of data to disk, use ``AppStorage``.

For situations where you need data to trickle back up again, use ``Binding``
(think mutable references to state).

## Topics

- ``State``
- ``Binding``
- ``ObservableObject``
- ``ObservableObject()``
- ``ObservationIgnored()``
- ``Published``
- ``Publisher``
- ``Cancellable``

### App Storage

- ``AppStorage``
- ``AppStorageKey``
- ``AppStorageValues``
- ``AppStorageProvider``
- ``DefaultAppStorageProvider``
- ``UserDefaultsAppStorageProvider``
- ``View/appStorageProvider(_:)``