What are some best practices for structuring PHP code to handle multiple sections on a website?

When handling multiple sections on a website in PHP, it is important to structure your code in a way that promotes organization and maintainability. One common approach is to use a modular architecture, where each section of the website is contained within its own separate file or directory. This helps to keep code related to each section isolated and easier to manage.

```php
// index.php
<?php
$page = isset($_GET['page']) ? $_GET['page'] : 'home';

switch($page) {
    case 'home':
        include 'pages/home.php';
        break;
    case 'about':
        include 'pages/about.php';
        break;
    case 'contact':
        include 'pages/contact.php';
        break;
    default:
        include 'pages/error.php';
        break;
}
?>
```

In this example, the main `index.php` file routes requests to different sections of the website based on the value of the `page` parameter in the URL. Each section is contained within its own separate PHP file in the `pages` directory, making it easy to add, remove, or modify sections without affecting other parts of the website.