In the app directory, nested folders are normally mapped to URL paths. However, you can mark a folder as a Route Group to prevent the folder from being included in the route's URL path. This allows you to organize your route segments and project files into logical groups without affecting the URL path structure.
- The naming of route groups has no special significance other than for organization. They do not affect the URL path.
 - Even though such routes inside (marketing) and (shop) share the same URL hierarchy, you can create a different layout for each group by adding a layout.js file inside their folders.
 - To opt specific routes into a layout, create a new route group (e.g. (shop)) and move the routes that share the same layout into the group (e.g. account and cart). The routes outside of the group will not share the layout (e.g. checkout).
 - To create multiple root layouts, remove the top-level layout.js file, and add a layout.js file inside each route group. This is useful for partitioning an application into sections that have a completely different UI or experience.
 - Routes that include a route group should not resolve to the same URL path as other routes.