title: Why "bootstrap" key in @NgModule is an array?
body: <p>As per my knowledge, there can be only one entry point of an application. As shown in the code snippet given below we are passing an array in the bootstrap key which decide the entry point of the application.</p>
  
  <pre><code>import { BrowserModule } from '@angular/platform-browser';
  import { NgModule } from '@angular/core';
  import { AppComponent } from './app.component';
  
  @NgModule({
    declarations: [AppComponent, MyComboboxComponent, 
                      CollapsibleDirective, CustomCurrencyPipe],
    imports: [BrowserModule],
    providers: [UserService, LessonsService],
    bootstrap: [AppComponent]
  
  })
  export class AppModule {
  
  }
  </code></pre>
  
  <p>P.S: I am learning Angular 2 and the question may sound silly :)</p>