# Source: https://nextjs.org/docs/app/api-reference/config/next-config-js/appDir.md

# appDir
@doc-version: 16.0.4



> This is a legacy API and no longer recommended. It is still supported for backward compatibility.

> **Good to know**: This option is **no longer** needed as of Next.js 13.4. The App Router is now stable.

The App Router ([`app` directory](/docs/app.md)) enables support for [layouts](/docs/app/api-reference/file-conventions/layout.md), [Server Components](/docs/app/getting-started/server-and-client-components.md), [streaming](/docs/app/api-reference/file-conventions/loading.md), and [colocated data fetching](/docs/app/getting-started/fetching-data.md).

Using the `app` directory will automatically enable [React Strict Mode](https://react.dev/reference/react/StrictMode). Learn how to [incrementally adopt `app`](/docs/app/guides/migrating/app-router-migration.md#migrating-from-pages-to-app).