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Welcome to the CodeIgniter course. CodeIgniter is a lightweight, open-source PHP framework for building web applications. It follows the model-view-controller pattern, keeps configuration small, and gives you the tools most projects need without forcing a large stack on you.

What you will learn

• Installing and configuring a CodeIgniter 4 project.
• How the request lifecycle, routing, controllers, views, and models fit together.
• Working with databases, migrations, and the query builder.
• File uploads, email, validation, sessions, flashdata, tempdata, and cookies.
• Caching, redirects, profiling, benchmarking, and asset handling.
• Internationalization and a practical security checklist.

How to use this course

Read the topics in order using the outline on the left. Each topic stands on its own, but later topics assume you have seen the earlier concepts. Code samples are short and are meant to be typed into a real project rather than copied blindly.

Before you start

• PHP 8.1 or newer with the intl and mbstring extensions.
• Composer installed and available in your terminal.
• A code editor and a local database such as MySQL or MariaDB.
• Basic familiarity with PHP syntax and HTML forms.

Examples target CodeIgniter 4. If you maintain a CodeIgniter 3 project, the MVC ideas still apply, but file names and some method signatures differ.

When you are ready, continue with Overview for the big picture, then Installing CodeIgniter to create your first project.