I'll help you convert the HTML template to PHP and demonstrate the different include functions. Let me create a modular PHP structure that breaks down the HTML into reusable components.

Key Differences Between Include Functions:

1. require()

• Fatal Error: If the file is not found, it produces a fatal error and stops script execution
• Use Case: For critical files that are essential for the application to work
• Example: Database connection files, configuration files

2. require_once()

• Same as require() but includes the file only once
• Prevents Duplicate Inclusion: If the file has already been included, it won't be included again
• Use Case: For files that should only be loaded once (like configuration files)

3. include()

• Warning Only: If the file is not found, it produces a warning but continues script execution
• Use Case: For optional files or content that won't break the application if missing
• Example: Optional sidebar content, non-critical components

4. include_once()

• Same as include() but includes the file only once
• Prevents Duplicate Inclusion: If the file has already been included, it won't be included again
• Use Case: For optional files that should only be loaded once

Best Practices:

1. Use require_once() for configuration files and critical includes
2. Use include_once() for optional components that should load only once
3. Use require() for critical files that might need to be included multiple times
4. Use include() for optional content that might need to be included multiple times

The PHP conversion maintains the original design while making it modular and reusable across different pages.