CodeIgniter is an open-source PHP web framework and application toolkit designed for server-side development. It implements a model-view-controller architecture to separate internal data representations from the user interface.
The framework utilizes a front-controller architecture to direct all incoming web requests through a single entry point for URI parsing and request dispatching. It includes a dependency injection container to resolve class dependencies and manage the lifecycle of core system components.
The toolkit provides capabilities for routing management, database interactions, and input validation. It supports the initialization of structured projects to facilitate the development of dynamic websites and rapid prototyping.