CodeIgniter is PHP based structure. Diving in CodeIgniter is not that you're left behind PHP. PHP is a server-side scripting language for creating dynamic web-based applications. CodeIgniter is a powerful PHP framework with a very small footprint, built for developers who need a simple and elegant toolkit to create full-featured web applications.
CodeIgniter’s latest version is 3.1.6. CodeIgniter’s Hooks feature provides a means to tap into and modify the inner workings of the framework without hacking the core files. When CodeIgniter runs it follows a specific execution process, diagramed in the Application Flow page.
CodeIgniter is based on model-View-controller (MVC) development pattern. MVC is a software approach that separates application logic from presentation. In practice, it allows minimal scripting to your webpages because the presentation is different from PHP Scripting.
CodeIgniter provides a rich set of libraries, which indirectly increases the speed of application development. The system is located on library system / libraries.
CI-Inviter is a library for the CodeIgniter PHP framework that allows users to import email contacts (with OpenInviter) and send selected contacts invitation emails.
CodeIgniter is easy to install, use and customize. Being MVC based framework, it offers flexibility and easy management. Active record implementation is simply superb and easy to remember.
The CodeIgniter uses a direct approach while handling models. CodeIgniter's operations are very clear as well as open, so it's easy to understand what's going on and so it's easy to use.
Using CodeIgniter, you can create your own cleaner URI lines
The helper is used as a function library, by this we can just load a helper class in the controller or view as well. CodeIgniter provide different types of helper class, such as url_helper, captcha_helper, email_helper etc. They all are located in system/helper.