Model-View-Controller CodeIgniter is based on the Model-View-Controller development pattern. MVC is a software approach that separates application logic from presentation. In practice, it permits your web pages to contain minimal scripting since the presentation is separate from the PHP scripting. The  Model  represents your data structures. Typically your model classes will contain functions that help you retrieve, insert, and update information in your database. The  View  is the information that is being presented to a user. A View will normally be a web page, but in CodeIgniter, a view can also be a page fragment like a header or footer. It can also be an RSS page, or any other type of “page”. The  Controller  serves as an  intermediary  between the Model, the View, and any other resources needed to process the HTTP request and generate a web page. CodeIgniter has a fairly loose approach to MVC since Models are not required. If you don’t need the added separation, or find that ma

Application Flow Chart The index.php serves as the front controller, initializing the base resources needed to run CodeIgniter. The Router examines the HTTP request to determine what should be done with it. If a cache file exists, it is sent directly to the browser, bypassing the normal system execution. Security. Before the application controller is loaded, the HTTP request and any user submitted data is filtered for security. The Controller loads the model, core libraries, helpers, and any other resources needed to process the specific request. The finalized View is rendered then sent to the web browser to be seen. If caching is enabled, the view is cached first so that on subsequent requests it can be served. https://codeigniter.com/userguide3/overview/appflow.html