→ Expression that evaluate to a function allowing annotation classes at design time

syntaxe : <decorator indicator><name>(<arguments>)
exemple : @Component()

→ app.component.ts

import {Component} from 'angular2/core'; // import du component

@Component({
  selector: 'app',
  template: '<h1>My App</h1>'
})
export class AppComponent {} // on exporte pour pouvoir importer ailleurs

→ main.ts

import {bootstrap} from 'angular2/platform/browser';
import {AppComponent} from './app.component';