The PRADO project was started by Qiang Xue, and was inspired by Apache Tapestry. The framework also borrowed ideas from Borland Delphi and Microsoft's ASP.NET framework. The first public release of PRADO came out in June 2004, but was written using the very limited and now outdated PHP 4 object model, which caused many problems. Qiang then re-wrote the framework for the new PHP 5 object model, and won the Zend PHP 5 coding contest with it.
Based on his experiences with PRADO, Qiang later went on to create the Yii framework, then a conceptual re-design of PRADO, to overcome the latter's drawbacks in high-performance, high-traffic scenarios. Subsequent implementation of template and configuration caching in later revisions eliminated most performance bottlenecks in its architecture, making it very well suited for creation of medium- to high-traffic websites, while still providing an exceptionally rapid way amongst PHP frameworks for the development of highly interactive web pages and applications.
Ajax-enabled active widgets (such as auto-complete input field, active button, active data grid) which can be updated, shown or paged dynamically, without having to reload and re-build the whole page
layered caching scheme, supporting separate caching of data queries and output fragments, via database, shared memory, memcached) for storing cached data, and dynamic cache entry validation upon retrieval
PRADO comes with a collection of official documentation, including a tutorial to develop a simple blog application, a reference guide describing all features, and a class reference for all properties, methods and events. The documentation is available in both HTML and Compiled HTML Help (.CHM) form.