CodeIgniter is an open-source PHP web application framework that is known for its simplicity, small footprint, and straightforward configuration. Here’s an overview of some key aspects and features of CodeIgniter:

1. Model-View-Controller (MVC) Architecture:
   • CodeIgniter follows the MVC architectural pattern, allowing developers to separate the application logic into three components: Model (handles data and business logic), View (handles presentation and user interface), and Controller (manages the flow of data between the Model and View).
2. Lightweight and Fast:
   • CodeIgniter is designed to be lightweight, making it easy to install and deploy. Its small footprint contributes to faster performance.
3. No Need for Template Language:
   • CodeIgniter allows the use of regular PHP syntax in views, eliminating the need for a template language. This can make it more approachable for developers who are already familiar with PHP.
4. Database Support:
   • CodeIgniter provides a database abstraction layer and supports various database drivers, making it easy to work with databases. It simplifies tasks such as database configuration, querying, and transactions.
5. Helpers and Libraries:
   • CodeIgniter includes a variety of helpers and libraries that simplify common tasks. These cover areas such as form handling, sessions, file uploading, encryption, and more.
6. Routing:
   • The routing system in CodeIgniter allows developers to define clean and SEO-friendly URLs. It provides flexibility in mapping URLs to controllers and methods.
7. Active Record Database Class:
   • CodeIgniter includes an Active Record implementation for database interactions. It provides a convenient way to perform database operations using an object-oriented syntax.
8. Security Features:
   • CodeIgniter has built-in security features, including input data filtering, output escaping, and CSRF protection, to help developers create more secure applications.
9. Error Handling:
   • CodeIgniter provides effective error handling and logging capabilities, helping developers identify and troubleshoot issues in their applications.
10. Extensibility:
    • CodeIgniter is designed to be easily extensible. Developers can create and use their own libraries, helpers, and third-party packages to enhance functionality.