intermediate

Route groups

Organize route trees without affecting URLs while separating layouts, teams, or product areas.

Route groups wrap folders in parentheses — `(marketing)`, `(shop)` — to organize files without affecting the URL. They enable different root layouts for product areas while sharing components and conventions.

					app/
  (marketing)/about/page.tsx   → /about
  (shop)/cart/page.tsx         → /cart

Groups help team ownership and layout separation; they do not replace authentication boundaries or API design.

On interviews: explain why URLs stay unchanged and when separate layout trees beat one global layout.

Common pitfalls: using groups expecting URL prefixes, duplicating providers across groups without reason, and confusing groups with parallel routes.

The trade-off is filesystem clarity versus more layout files to maintain.

Checklist:

Parentheses exclude segment from URL.
Assign layouts per product area when needed.
Do not use groups for auth alone.
Document team conventions for folder names.