Route Groups let you group routes and share layouts without affecting the URL path. The folder name in parentheses is not part of the route. It’s useful for organizing large apps (e.g., separate marketing vs app) while keeping clean URLs.
Expanding on the short answer — what usually matters in practice:
A tiny example (an explanation template):
// Example: discuss trade-offs for "route-groups-`(group)`:-what-are-they-and-why-us"
function explain() {
// Start from the core idea:
// Route Groups let you group routes and share layouts without affecting the URL path. The fo
}