2.1. The MVC Pattern2.1.1. MVC Layering2.1.2. Layer Separation Beyond MVC2.1.3. Symfony's MVC Implementation2.1.4. Symfony Core Classes2.2. Code Organization2.2.1. Project Structure: Applications, Modules, and Actions2.2.2. File Tree Structure2.3. Common Instruments2.3.1. Parameter Holders2.3.2. Constants2.3.3. Class Autoloading2.4. Summary