Dependency Injection in Angular compared to .Net Dependency Injection

Technically, all services in Angular are scoped. However, they can be scoped to:

1. Root - an instance of a service provided in the root (or injected in AppModule) is shared between all modules and components. This is also what we call a singleton, scoped to root (entire app).

@Injectable({
  providedIn: 'root',
})

2. Module - an instance of a service provided in a lazy-loaded module is shared between the components of the module. This is also a singleton, but scoped to a module.

@NgModule({
  ...
  providers: [{ provide: LocationStrategy, useClass: HashLocationStrategy }]
})

3. Component - an instance of a service injected into a component only lives while that component lives. Once that component is destroyed, the instance o the service is also destroyed. Multiple instances of the same component each have their own instance of the service.

@Component({
  ...
  providers: [{ provide: ItemService, useValue: { name: 'lamp' } }]
})

This section of the documentation touches upon the hierarchy of injection: https://angular.io/guide/hierarchical-dependency-injection