How do you configure injectors with providers at different levels?

You can configure injectors with providers at different levels of your application by setting a metadata value. The configuration can happen in one of three places,

1. In the @Injectable() decorator for the service itself
2. In the @NgModule() decorator for an NgModule
3. In the @Component() decorator for a component

Practical Code Example

// Provider Configuration at Different Levels:
// 1. Root level: @Injectable({ providedIn: 'root' }) -> Single app-wide instance
// 2. Component level: @Component({ providers: [LocalService] }) -> Isolated instance per component