Short: symfony 2 is a PHP application framework. A framework includes tools and methods for building professional software.
We use symfony 2 because it is a sophisticated and internationally known stable open source development environment. The active community always develops the core of software and ensures therefore a long service life. The symfony 2 framework does not dictate which components have to be used, instead these can be chosen depending on the situation.
Invest in the task, not in the technology
With a framework an ideal, robust base, exists on which the software can be installed. The predefined components of a framework can be modularly assembled and individually adapted. With a framework, less code must be written, resulting in fewer errors. The developers can concentrate more on the task and invest their time in the development of business-related functionality. A framework helps one to structure the work better and to achieve a higher level of availability again. It also simplifies the maintainability and scaling through adherence to standards and development guidelines. These guidelines facilitate the integration and interface creation to other applications.
A framework offers flexibility to create customized software solutions.