Yii is a high-performance PHP framework suitable for developing Web2.0 applications. It is free, open source, and based on PHP5 for Web application development. The code is concise, DRY designed and encourages rapid development. It works to simplify your application development and helps ensure a very efficient, scalable and maintainable end product. With extremely optimized performance, Yii is a good choice for any size project. However, it is built with enterprise applications in mind. You have complete control from top to bottom (demo to persistence) to configure the configuration in line with your business development guidelines. It comes with tools to help test and debug applications, and has clear and comprehensive documentation.