php - Understanding laravel 'auth' and 'web' middleware -

i have strange behavior on 1 of route groups have defined e.g

route::group(['prefix' => 'admin', 'middleware' => ['web','auth']], function (){   //admin routes  } ); 

whenever defined 'middleware' => ['web','auth'], routes accessible after login , without 'web' redirected / home.

what thought that , 'web' default middleware injected ,please correct me if wrong. otherwise there other setting affecting behavior ?

laravel comes web middleware groups contains common middleware may want apply web ui routes. web middleware group automatically applied default routes.php file routeserviceprovider.