angular router
const routes: Routes = [
  { path: '',   redirectTo: '/first-component', pathMatch: 'full' }, // redirect to `first-component`
  { path: 'first-component', component: FirstComponent },
  { path: 'second-component', component: SecondComponent },
  { path: '**', component: PageNotFoundComponent },  // Wildcard route for a 404 page
];
