title: What does @Injectable mean?
body: <p>Does <code>@Injectable</code> mean that we can inject <code>MyService</code> into other classes or that we can inject other classes into <code>MyService</code>?</p>
  
  <pre><code>@Injectable({
    providedIn: 'root'
  })
  export class MyService {
  
    constructor() { }
  }
  </code></pre>