Symfony2 can handle configuration in different formats: YAML, XML, and annotations. The main configuration files within app/config are provided with the YAML format. XML is usually harder to read, and is used only with third-party bundles.
While both YAML and XML configuration are pretty straightforward and need no explanations, we should stop by annotations for a while. As an example, see the AppBundle/Controller/DefaultController class:
namespace AppBundle\Controller;
use Sensio\Bundle\FrameworkExtraBundle\Configuration\Route;
use Symfony\Bundle\FrameworkBundle\Controller\Controller;
class DefaultController extends Controller
{
/**
* @Route("/", name="homepage")
*/
public function indexAction(Request $request)
{
// replace this example code with whatever you need
return $this->render('default/index.html.twig', array(
'base_dir' => realpath(
$this->container
->getParameter...