What are the different approaches for building navigation in PHP websites, and how do they impact SEO and user experience?

When building navigation in PHP websites, it's important to consider both SEO and user experience. One approach is to use a dynamic navigation system that pulls navigation links from a database, allowing for easy updates and customization. Another approach is to hardcode navigation links directly into the PHP files, which can be simpler but less flexible. Dynamic navigation system example:

<?php
// Connect to database and retrieve navigation links
$nav_links = array(
    'Home' => 'index.php',
    'About Us' => 'about.php',
    'Services' => 'services.php',
    'Contact' => 'contact.php'
);

// Display navigation links
echo '<ul>';
foreach ($nav_links as $title => $url) {
    echo '<li><a href="' . $url . '">' . $title . '</a></li>';
}
echo '</ul>';
?>
```

Hardcoded navigation links example:

```php
<?php
// Hardcoded navigation links
$nav_links = array(
    'Home' => 'index.php',
    'About Us' => 'about.php',
    'Services' => 'services.php',
    'Contact' => 'contact.php'
);

// Display navigation links
echo '<ul>';
foreach ($nav_links as $title => $url) {
    echo '<li><a href="' . $url . '">' . $title . '</a></li>';
}
echo '</ul>';
?>