Symfony4 has been released on November 30th 2017. Unlike Symfony3 that was "just" an improved Symfony2. Symfony4 rethinks the way we can develop with this framework. One of the major feature of this version is that it allows to use Symfony Flex to automate the most common tasks and it eventually introduces a simpler directory structure. The second major feature it that it is now "micro by default", therefore the Silex micro framework based on Symfony components was discontinued.