What is auth.authenticate view in laravel 5.2 auth

What is the use of auth.authenticate view, as there is no file under the auth direcirectory named "authenticate", also what is loginView here?

As mentioned in this code:

   public function showLoginForm()
    {
        $view = property_exists($this, 'loginView')
                    ? $this->loginView : 'auth.authenticate';

        if (view()->exists($view)) {
            return view($view);
        }

        return view('auth.signin');
    }

via Chebli Mohamed