Yii is a PHP framework based on object-oriented PHP5 that was developed by Qiang Xue in 2008. It is a high-performance, component-based framework for developing large-scale web applications using the Model-View-Controller (MVC) pattern. Key features include database access, form validation, authentication, caching, and code generation capabilities. While Yii supports developing many types of web applications, it does not fully utilize the most modern PHP 5.3/6 features, so its developers have decided to rewrite the entire framework from scratch.