Yii is a high-performance modern PHP framework best for developing both web applications and APIs.
Yii is pronounced as Yee or [ji:], and is an acronym for "Yes It Is!"
This is often the accurate, and most concise response to inquires from those new to Yii:
Is it fast? ... Is it secure? ... Is it professional? ... Is it right for my next project? ... Yes, it is!
Yii is a free, open-source Web application development framework written in PHP5 that promotes clean, DRY design and encourages rapid development. It works to streamline your application development and helps to ensure an extremely efficient, extensible, and maintainable end product.
Being extremely performance optimized, Yii is a perfect choice for any sized project. However, it has been built with sophisticated, enterprise applications in mind. You have full control over the configuration from head-to-toe (presentation-to-persistence) to conform to your enterprise development guidelines. It comes packaged with tools to help test and debug your application, and has clear and comprehensive documentation.
To learn more about what Yii brings to the table, check out the features section.
Yii is the brainchild of its founder, Qiang Xue, who started the Yii project on January 1, 2008. Qiang previously developed and maintained the Prado framework. The years of experience gained and developer feedback gathered from that project solidified the need for an extremely fast, secure and professional framework that is tailor-made to meet the expectations of Web 2.0 application development. On December 3, 2008, after nearly one year's development, Yii 1.0 was formally released to the public.
Its extremely impressive performance metrics when compared to other PHP-based frameworks immediately drew very positive attention and its popularity and adoption continues to grow at an ever increasing rate.
On October 2014 Yii 2.0.0 was released which is a complete rewrite over the previous version that was made in order to build a state-of-the-art PHP framework by keeping the original simplicity and extensibility of Yii while adopting the latest technologies and features to make it even better.