Symfony is a PHP based framework
Symfony is a PHP5-based framework produced by SensioLabs. Symfony has a basic architecture as well as many basic functionalities, which is a tremendous time-saver for developers. Many of these features can be used again for various projects with Symfony, meaning that finished modules – bundles – can be incorporated into the project. The increasing popularity of Symfony ensures that there is a rising number of premade bundles – similar to plugins and extensions of various content management systems like WordPress.
Symfony provides developers with many advantages thanks to its modular construction
What’s interesting about Symfony is the high modularity of the subcomponents and the low dependencies among them. Further advantages of Symfony: there are built-in template engines, Symfony offers the opportunity to use the Twig engine and simple PHP. URLS are automatically redirected from one configuration to the correct PHP class. In addition, there is the change to let URLs be generated dynamically based on their configuration. If the configuration changes, the developer will not need to adapt every single URL in the templates. Symfony also uses standard formats, which means that not only can the routes be configured, but the format that should be delivered can also be specified and easily modified in the configuration. Caching is also possible with Symfony: caching (the unique generation and multiple issue of dynamic pages) is very important for websites with many visitors. Symfony has a simple and already built-in system for this purpose.
You can find more information on Symfony on Wikipedia: https://en.wikipedia.org/wiki/Symfony