What are the key differences between designing a website with HTML and using PHP to dynamically generate content?

When designing a website with HTML, the content is static and does not change unless manually updated. On the other hand, using PHP allows for dynamic content generation, where the website can display different information based on user input or other variables. PHP can interact with databases, handle form submissions, and create personalized user experiences.

<?php
// Example PHP code snippet for dynamically generating content
$dynamic_content = "Welcome, " . $_GET['username'] . "!"; // Accessing user input from the URL
echo $dynamic_content;
?>