title: How `angular2` exports a component?
body: <p>I am creating a component like this: ( from the sample )</p>
  
  
  
  <pre class="lang-ts prettyprint-override"><code>import {Component} from 'angular2/core';
  
  @Component({
      selector: 'my-app',
      template: '&lt;h1&gt; ~ My First Angular 2-0 App By Gulp Automation ~ &lt;/h1&gt;'
  })
  
  export class AppComponent { } //what it is exporting here?
  </code></pre>
  
  <p>and importing to another module:</p>
  
  <pre class="lang-ts prettyprint-override"><code>import {bootstrap}    from 'angular2/platform/browser'
  import {AppComponent} from './app.component' //what it's imports here
  
  bootstrap(AppComponent); //it works.
  </code></pre>
  
  <p>in index.html :</p>
  
  <pre class="lang-ts prettyprint-override"><code>&lt;script&gt;
        System.config({
          packages: {        
            app: {
              format: 'register', //what is means?
              defaultExtension: 'js'
            }
          }
        });
        System.import('app/boot')
              .then(null, console.error.bind(console));
      &lt;/script&gt;
  </code></pre>
  
  <p>I am not able to understand the logic behind, any one help me please?</p>
  
  <p>thanks in advance.</p>