HMVC stands for Hierarchical Model View Controller Modular Extensions makes the CodeIgniter PHP framework modular Modules are groups of independent components, typically model, controller and view, arranged in an application modules sub-directory, that can be dropped into other CodeIgniter applications Module Controllers can be used as normal Controllers or HMVC Controllers and they can be used to help you build view partials By promoting modularity, HMVC allows systems to be more easily extended by simply adding or replacing modules To use HMVC functionality, controllers must extend the MX_Controller class