What is "symfony"
Symfony is a full-stack PHP framework developed and maintained by Sensio Labs.
Symfomy is a framework, a set of development tools and methodologies. Moreover, Symfony is also a philosophy and a community.
Components
In addition to being a full-stack framework, Symfony is also a set of decoupled and independent components.
Information
This tag is specific to the Symfony 2, which is available on official website.
If your question is about Symfony 1.x, please use symfony-1.
As of 4 April 2014, the latest stable version of Symfony 2 is version 2.4.3.