Yii is a high performance PHP framework with a very short learning curve.Its a free open source web application development framework that promotes clean, dry design.Its component based design allows the user to customize it based on their requirements without directly modifying it. Yii is a perfect choice for any sized project. The user is having full control over the configuration. It comes packaged with tools to help,test and debug the application and has clear and comprehensive documentation. Yii is a generic web programming framework that is lightweight and equipped with sophisticated caching solutions. It is especially suitable for developing high traffic applications.