Fabulous PHP frameworks: CodeIgniter
CodeIgniter combines an easy installation with simplicity and flexibility, but is limited in features compared to competitors
Like the Zend Framework, CodeIgniter uses the front-end controller pattern. All HTTP requests are received by index.php, sent to the proper processing routines through a routing system, passed through a security system (which shields the application's controllers from malicious input), then finally handed to a controller. The controller loads the model, processes the request, and sends the result to the view system.
CodeIgniter helpers, libraries, extensions