Many developers use the HTML comment in order to analyse the page by using the “view source” feature provided by almost all browsers. However, these comments will be visible to everyone. Also, they are sent from the server to the client and that could take a lot of needless bytes.
If you don’t need to display your HTML comment by using “view source” of if you don’t want to make visible them for all users, you might use the following simple rule:
<!-- Hi there, I'm an HTML comment -->
The above HTML code is a comment. You can replace that by following:
<!-- <?php Hi there, I'm a "invisible" comment ?> -->
<?php // Hi there, // I'm a "invisible" comment ?>