Previously we said that controllers accept request and return response. The response, however, can often be any content type. The production of actual content is something controllers delegate to the templating engine. The templating engine then has the capability to turn the response into HTML, JSON, XML, CSV, LaTeX, or any other text-based content type.

In the old days, programmers mixed PHP with HTML into the so called PHP templates (.php and .phtml). Though still used with some platforms, this kind of approach is considered insecure and lacking in many aspects. One of which was cramming business logic into template files.

To address these shortcomings, Symfony packs its own templating language called Twig. Unlike PHP, Twig is meant to strictly express presentation and not to thinker about program logic. We cannot execute any of the PHP code within the Twig. And the Twig code is nothing more than an HTML with a few special syntax types.

Twig defines three types of special syntax...