What is the purpose of the forRoot() and forChild() methods in Angular?

Short answer: Used mainly by feature modules that provide services and routes. forRoot() configures and provides singleton services for the app. Usually called in the root module. forChild() configures child routes without providing new service instances.

Example code

RouterModule.forRoot(routes) // for root app routing RouterModule.forChild(childRoutes) // for feature module routing

Real-world example (ShopNest)

ShopNest admin can be built in Angular with modules/components, services for API calls, and reactive forms for product edit.

Say this in the interview

1. Define — one clear sentence (the short answer above).
2. Example — relate it to a project like ShopNest or your real work.
3. Trade-off — when you would not use it.