How can PHP be used to dynamically include content from separate files into a web page?

To dynamically include content from separate files into a web page using PHP, you can use the `include` or `require` functions. These functions allow you to pull in the contents of another PHP file at the location where the function is called. This can be useful for reusing code, separating concerns, and making your code more modular.

<?php
include 'header.php'; // include header content
include 'sidebar.php'; // include sidebar content
include 'main_content.php'; // include main content
include 'footer.php'; // include footer content
?>