This document discusses the history and evolution of the Symfony framework. Symfony 1 started as a collection of existing PHP libraries and adopted concepts from other frameworks. Symfony 2 is a major evolution based on Symfony 1's concepts but with improvements such as increased speed, easier use, and support for new PHP 5.3 features. Symfony 2 also uses standalone PHP components and improved architecture, development tools, and documentation to provide a more developer-friendly experience. While Symfony 2 promises these improvements, the document notes that a stable release was not expected until late 2010.