Comments are used for understanding the code to the Developer or Programmer.These Comments are invisible for Users ie.in Web browser and only visible in coding only. However PHP also contains Comments.
php comments are two types:

	Single Line Comments (SLC)
	Multi Line Comments (MLC)

           Single line comments are applied only for a Single Line of code. Single Line Comments are used with '//'.

<?php
 // This is Single Line Comment
?>

           Multi line comments are used for commenting group of lines or group of code or group of statements.
The Symbols ' /*.......*/ ' are used for Multi Line Comment.

<?php 
 /* This is
 Multi Line
 Comment 
 */
?>