title: what does $ mean in Angular 7
body: <p>I have some confusion in variable declaration.</p>
  
  <blockquote>
    <p>what does $ mean in heroes$</p>
  </blockquote>
  
  <p>Angular 4</p>
  
  <pre><code>export class HeroSearchComponent implements OnInit {
  heroes: Observable&lt;Hero[]&gt;;
  private searchTerms = new Subject&lt;string&gt;();
  
  constructor(
   private heroSearchService: HeroSearchService,
   private router: Router) {}
  </code></pre>
  
  <p>Angular 7+</p>
  
  <pre><code> export class HeroSearchComponent implements OnInit {
   heroes$: Observable&lt;Hero[]&gt;;
   private searchTerms = new Subject&lt;string&gt;();
   constructor(private heroService: HeroService) {}
  
       // Push a search term into the observable stream.
            search(term: string): void {
            console.log(term);
              this.searchTerms.next(term);
          }
  </code></pre>
  
  <ul>
  <li><p>i have confusion in angular 7 ver where
  heroes is assigned with $ variable.</p></li>
  <li><p>i tried to remove $ symbol from var then code doesn't works.</p></li>
  <li><p>any suggestion is most welcome</p></li>
  </ul>