# File Naming Conventions File-based routing requires that you follow a few simple file naming conventions to ensure that your routes are generated correctly. The concepts these conventions enable are covered in detail in the [Route Trees & Nesting](./route-trees.md) guide. | Feature | Description | | ---------------------------------- | -------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------- | | **`__root.tsx`** | The root route file must be named `__root.tsx` and must be placed in the root of the configured `routesDirectory`. | | **`.` Separator** | Routes can use the `.` character to denote a nested route. For example, `blog.post` will be generated as a child of `blog`. | | **`$` Token** | Route segments with the `$` token are parameterized and will extract the value from the URL pathname as a route `param`. | | **`_` Prefix** | Route segments with the `_` prefix are considered to be pathless layout routes and will not be used when matching its child routes against the URL pathname. | | **`_` Suffix** | Route segments with the `_` suffix exclude the route from being nested under any parent routes. | | **`-` Prefix** | Files and folders with the `-` prefix are excluded from the route tree. They will not be added to the `routeTree.gen.ts` file and can be used to colocate logic in route folders. | | **`(folder)` folder name pattern** | A folder that matches this pattern is treated as a **route group**, preventing the folder from being included in the route's URL path. | | **`[x]` Escaping** | Square brackets escape special characters in filenames that would otherwise have routing meaning. For example, `script[.]js.tsx` becomes `/script.js` and `api[.]v1.tsx` becomes `/api.v1`. | | **`index` Token** | Route segments ending with the `index` token (before any file extensions) will match the parent route when the URL pathname matches the parent route exactly. This can be configured via the `indexToken` configuration option (supports both strings and regex patterns), see [options](../api/file-based-routing.md#indextoken). | | **`.route.tsx` File Type** | When using directories to organise routes, the `route` suffix can be used to create a route file at the directory's path. For example, `blog.post.route.tsx` or `blog/post/route.tsx` can be used as the route file for the `/blog/post` route. This can be configured via the `routeToken` configuration option (supports both strings and regex patterns), see [options](../api/file-based-routing.md#routetoken). | > **💡 Remember:** The file-naming conventions for your project could be affected by what [options](../api/file-based-routing.md) are configured. ## Dynamic Path Params Dynamic path params can be used in both flat and directory routes to create routes that can match a dynamic segment of the URL path. Dynamic path params are denoted by the `$` character in the filename: | Filename | Route Path | Component Output | | --------------------- | ---------------- | --------------------- | | ... | ... | ... | | ʦ `posts.$postId.tsx` | `/posts/$postId` | `` | We'll learn more about dynamic path params in the [Path Params](../guide/path-params.md) guide. ## Pathless Routes Pathless routes wrap child routes with either logic or a component without requiring a URL path. Non-path routes are denoted by the `_` character in the filename: | Filename | Route Path | Component Output | | -------------- | ---------- | ---------------- | | ʦ `_app.tsx` | | | | ʦ `_app.a.tsx` | /a | `` | | ʦ `_app.b.tsx` | /b | `` | To learn more about pathless routes, see the [Routing Concepts - Pathless Routes](./routing-concepts.md#pathless-layout-routes) guide.