What is CodeIgniter? - Tutorial


CodeIgniter is a powerful PHP framework designed for rapid web application development. It follows the Model-View-Controller (MVC) architectural pattern, providing a structured approach to building dynamic and scalable web applications.

Features of CodeIgniter

  • Lightweight and easy to install
  • Simple and intuitive syntax
  • Support for MVC architecture
  • Excellent performance
  • Database abstraction with query builder
  • Built-in form and data validation
  • Security features like XSS filtering and CSRF protection
  • Extensive library of helpers and plugins
  • Flexible routing system
  • Easy integration with third-party libraries

Getting Started with CodeIgniter

Step 1: Installation

To get started with CodeIgniter, follow these steps:

  1. Download the latest version of CodeIgniter from the official website.
  2. Extract the downloaded archive and place it in your web server's document root.
  3. Configure your database settings in the config/database.php file.

Step 2: Creating a Controller

In CodeIgniter, controllers are responsible for handling user requests and generating responses. Create a new file called MyController.php in the application/controllers directory and add the following code:

class MyController extends CI_Controller {
  public function index() {
    echo "Hello, CodeIgniter!";

Step 3: Routing

By default, CodeIgniter uses a convention-based routing system. Open the config/routes.php file and add the following line:

$route['default_controller'] = 'MyController';

Step 4: Accessing the Application

You can now access your CodeIgniter application by navigating to http://localhost/ in your web browser. The output should display "Hello, CodeIgniter!".

Common Mistakes

  • Not following the MVC pattern
  • Ignoring proper security practices
  • Not leveraging the available CodeIgniter libraries and helpers
  • Failure to sanitize user input
  • Not updating to the latest version of CodeIgniter

Frequently Asked Questions (FAQs)

1. Is CodeIgniter suitable for large-scale applications?

Yes, CodeIgniter can be used for large-scale applications. However, for extremely complex projects, other frameworks like Laravel may offer more extensive features.

2. Can I use CodeIgniter with a different database system?

Yes, CodeIgniter supports multiple databases, including MySQL, PostgreSQL, SQLite, and more. You can configure the database settings in the config/database.php file.

3. How can I handle form validation in CodeIgniter?

CodeIgniter provides a built-in form validation library. You can define validation rules in your controller and use the library to handle form validation.


CodeIgniter is a lightweight PHP framework that enables developers to build robust and scalable web applications. Its simplicity, performance, and rich feature set make it a popular choice for developers of all levels of experience. By following this tutorial, you have learned the basics of CodeIgniter, its features, and how to get started with it. Remember to follow best practices and leverage the framework's security and optimization features to ensure the success of your CodeIgniter projects.