Is there a specific rule or definition regarding the necessity of opening and closing HTML tags when using PHP scripts?

When using PHP scripts to generate HTML content, it is important to remember to properly open and close HTML tags to ensure that the markup is valid. This can be achieved by echoing out the opening and closing tags within the PHP code, or by switching in and out of PHP mode when necessary.

<?php
echo "<div>";
// PHP logic here
echo "</div>";
?>