An app is a focused view that handles tasks that are too complex for a complication,
tile, or notification. Apps on Wear OS are similar to a mobile app's main user interface. Use
surfaces such as tiles, complications, and notifications to accomplish simple tasks, but link
these surfaces into an app to carry out more complex tasks.


Review the following principles and use cases for a better understanding of apps.

## UX principles


Design apps with the following principles in mind:

Focus
:   Focus apps on critical tasks to help people get things done within seconds to avoid
    ergonomic discomfort or arm fatigue

Shallow and linear
:   Avoid hierarchies deeper than two levels. Show navigation inline

Scroll
:   Views can scroll. This is a natural gesture for users to see more content on the watch

## When to use an app


Use apps in the following situations:

For additional info
:   Focus apps on critical tasks to help people get things done within seconds to avoid
    ergonomic discomfort or arm fatigue.

For richer interactions
:   To provide richer interaction than a complication or Tile.

For adjusting preferences
:   To provide access to education and preferences.

## Building an app

Wear OS supports two distinctive ways of building an app:

- [Compose-based UI](https://developer.android.com/training/wearables/compose)
- [View-based UI](https://developer.android.com/training/wearables/views)

Compose for Wear OS is a modern declarative UI toolkit and is the recommended
approach for building apps on Wear OS.

Compose-based UIs in most cases result in less code and accelerates the development process of
Android apps as a whole. See [Why Compose](https://developer.android.com/jetpack/compose/why-adopt) for more
information on the general advantages of a declarative UI framework.

The Compose Material Catalog for Wear OS follows material styling, includes built in
accessibility, and implements material theming, which allows you to customize the design for your
brand. Compose for Wear OS offers more components than are available with Views, and is designed
to help you create user experiences that conform to Wear OS design guidelines.

If you have an existing Wear OS app with a large view-based codebase, it's possible to gradually
adopt Compose by using the
[Compose Interoperability APIs](https://developer.android.com/jetpack/compose/interop/interop-apis) rather than
having to rewrite the whole codebase.

## Guides for creating apps with Compose

[Use Jetpack Compose on Wear OS](https://developer.android.com/training/wearables/apps/lists)
:   Learn how to build with Compose for Wear OS.

[Create lists](https://developer.android.com/training/wearables/compose/lists)
:   Learn how to create lists that are optimized for wearable devices.

[Navigating with Compose for Wear OS](https://developer.android.com/training/wearables/compose/navigation)
:   Learn more about building navigation in Compose.

[Compose performance on Wear OS](https://developer.android.com/training/wearables/compose/performance)
:   Learn more about performance and testing your app performance.