What is the difference between using include and echo in PHP for including CSS files?

Using include in PHP is typically used for including PHP files, not CSS files. When including CSS files, it is more appropriate to use echo to output the link tag directly into the HTML. This way, the browser can properly interpret the CSS file and apply the styles to the webpage.

<?php
echo '<link rel="stylesheet" type="text/css" href="styles.css">';
?>