Route groups and parallel routes

Structure that the URL never sees

A folder in parentheses is a route group: it organises files and can carry its own layout, but contributes nothing to the URL. Use it to give a marketing section and an application section separate root chrome while both live at the top level.

Parallel routes let one layout render several independent segments at once, each with its own loading and error state. The classic case is a dashboard where a feed and an activity panel load at different speeds and neither should block the other.

Intercepting routes pair with them to produce the photo-modal pattern: clicking a thumbnail opens the detail route in an overlay, while loading that same URL directly renders the full page.