What are some key considerations when designing a navigation system in PHP for a website?

When designing a navigation system in PHP for a website, it is important to consider the structure and organization of the navigation elements, user experience, and scalability. It is also crucial to ensure that the navigation is responsive and accessible across different devices.

<nav>
    <ul>
        <li><a href="index.php">Home</a></li>
        <li><a href="about.php">About Us</a></li>
        <li><a href="services.php">Services</a></li>
        <li><a href="contact.php">Contact</a></li>
    </ul>
</nav>