application/                    --- Main CodeIgniter source files
    config/
        production/             --- Configuration when ENVIRONMENT is set as "production"
        autoload.php            --- By default, some files are loaded for this repo
        ci_bootstrap.php        --- Core configuration file for all sites
        database.php            --- Need to verify to ensure connection with MySQL database
        email.php               --- Created to centralize email configuration (default: using Mailgun)
        form_validation.php     --- Created to centralize validation forms for all forms, include ReCAPTCHA settings
        routes.php              --- Changed default controller from Welcome to Home
    controllers/                --- Controllers for Frontend Website; extends from MY_Controller (except Cli)
        Cli.php                 --- Utility function that can only be called from command line
        Home.php                --- Default controller for Frontend Website
    core/                       --- Extending CodeIgniter core classes; can also be used within modules
        MY_Controller.php       --- Important class which contains shared logic of all controllers
        MY_Loader.php           --- Required for HMVC extension
        MY_Model.php            --- Contains shared function for model classes
        MY_Router.php           --- Required for HMVC extension
    helpers/                    --- Contains custom helper functions being used throughout this repo
    language/                   --- Preset language files
    libraries/                  --- Custom libraries (e.g. Form Builder, System Message)
        MY_Email.php            --- Enhanced email library, includes work with Mailgun API
    models/                     --- Sample model extending from MY_Model
    modules/                    --- Each module can be accessed by https://{base_url}/{module_name}/{module_controller}/, etc.
        admin/                  --- Module for Admin Panel
            config/             --- Configuration for Admin Panel (overriding application/config/)
            controllers/        --- Controllers for Admin Panel; also extends from MY_Controller
            libraries/          --- Libraries specific for Admin Panel
            models/             --- Models only being used in Admin Panel
            views/              --- Views for Admin Panel; can reuse Frontend views, or override by using same path/filename
        adminlte/               --- Module with AdminLTE widgets
        api/                    --- Another module specific for API endpoints
    third_party/				--- 3rd party files (HMVC extension, Grocery CRUD, Rest Server, etc.)
    views/                      --- Views for Frontend Website, can also be used by modules unless overrided
assets/                         --- Folder for public files
    api/                        --- Swagger UI assets
    dist/                       --- Post-processed scripts and images via gulp tasks (don't manually edit files here!)
    grocery_crud/               --- Asset files from Grocery CRUD library
    image_crud/                 --- Asset files from Image CRUD library
    uploads/                    --- Default folder for upload files, where permission should set as writable
gulpfile.js/                    --- Task runner following gulp-starter practice
    tasks/                      --- Gulp tasks
    config.js                   --- Configuration for Gulp tasks
screenshots/                    --- Screenshot images for preview
sql/                            --- MySQL files
    backup/                     --- Files which will be created when backup database from CLI
    core/                       --- Files contains core data (e.g. Ion Auth)
    latest.sql                  --- Latest version of all preset data
src/                            --- Folder for non-public source files
    css/                        --- Custom CSS files append to each site
    images/                     --- Source image files before optimization
    js/                         --- Custom CSS files append to each site
    sass/                       --- SASS files for styling
    theme/                      --- Default folder for additional theme files
system/                         --- CodeIgniter core files (unchanged as clean CI3 installation)
.htaccess                       --- URL rewrite for Apache web server (require mod enabled)