Introduction to CodeIgniter — What is CodeIgniter? — Features and Advantages — CodeIgniter vs Other Frameworks — MVC Architecture Overview Installation & Setup — Downloading CodeIgniter — Directory Structure Explanation — Configuration Files — Setting up Base URL — Running on XAMPP/WAMP/Localhost MVC Pattern Deep Dive — Understanding Model — Understanding View — Understanding Controller — How MVC Works in CodeIgniter Routing and URL Handling — What is Routing? — Default Controller — Custom Routes — URI Segments Controllers — Creating a Controller — Passing Data to Views — Calling Models from Controllers — Loading Helpers & Libraries Views — Creating View Files — Passing Data to Views — Loading Multiple Views — Using Template System Models — Creating and Using Models — Loading Models in Controllers — Writing Queries in Models — Return Data from Models Database Operations (CRUD) — Connecting to Database — SELECT Query — INSERT Query — UPDATE Query — DELETE Query — Using Query Builder Form Handling and Validation — Creating Forms in View — Submitting Forms to Controller — Using Form Validation Library — Showing Error Messages — Retaining Input Values Session & Flash Data — Setting Session Data — Accessing Session Data — Destroying Session — Flashdata for One-Time Messages User Authentication System — Login & Logout System — Registration System — Password Encryption — Session-based Access Control — Admin/User Role Management Libraries & Helpers — What are Helpers? — Commonly Used Helpers — Custom Helpers — Loading and Using Libraries — Creating Custom Libraries Email Functionality — Setup Email Configuration — Sending Email — Attaching Files — Email Templates File Uploading — Upload Configuration — Uploading Images/Docs — Validating File Types — Handling Upload Errors Pagination — Pagination with Query Builder — Pagination Links Styling — Using Pagination Library Search Functionality — Basic Search with SQL — Advanced Search with Filters — Search with Pagination Ajax Integration — Sending Data with jQuery Ajax — Displaying Ajax Responses — Ajax Form Submission — Loading Data Dynamically Template Integration — Bootstrap Integration — AdminLTE or SB Admin in CodeIgniter — Master Layout File RESTful API in CodeIgniter — What is REST API? — Creating RESTful Endpoints — JSON Response — Testing API with Postman — Securing API with API Key Security in CodeIgniter — XSS and CSRF Protection — SQL Injection Prevention — Form Token Implementation — Input Sanitization CodeIgniter Best Practices — Folder Structure — Reusability — Coding Standards — Error Handling CodeIgniter 3 vs CodeIgniter 4 — Differences in Architecture — Routing Differences — Namespaces & Autoloading — Better Practice Recommendation Deploying CodeIgniter App — Preparing for Production — htaccess Setup — Hosting and Database Migration — Debugging & Error Logs