Symfony

Symfony is a set of PHP components and a free MVC framework written in PHP. It provides modular, adaptable features that make web development easier and faster. The French web agency SensioLabs originally built the framework as Sensio Framework.

Tired of rebuilding the same user management, ORM, etc. over and over, they developed the framework for their own needs. Since these problems were the same for other developers, the code was eventually shared with the developer community.

The project then became Symfony (in line with the creator's wish to keep the S and F initials of Sensio Framework), and then Symfony2 from version 2 onwards. Symfony 2 broke compatibility with the 1.x branch. From version 2 on, compatibility breaks between versions are documented to ease upgrades.
On 5 September 2017, Symfony passed the one-billion-download mark.