How can a WYSIWYG editor impact the inclusion of PHP content and HTML tags in a website?

A WYSIWYG editor can sometimes inadvertently modify or strip out PHP content and HTML tags when editing a website. To ensure that PHP content and HTML tags are included correctly, it is important to use a WYSIWYG editor that supports these elements or to manually edit the code outside of the editor.

<?php
// Example PHP code snippet
echo "Hello, world!";
?>