PHP supports 'C', 'C++' and Unix shell-style comments. For example:
<?php
echo "This is a test"; // This is a one-line c++ style comment
/* This is a multi line comment
yet another line of comment */
echo "This is yet another test";
echo "One Final Test"; # This is shell-style style comment
?>
The "one-line" comment styles actually only comment to the end of the line or the current block of PHP code, whichever comes first.
<h1>This is an <?# echo "simple";?> example.</h1> <p>The header above will say 'This is an example'.
You should be careful not to nest 'C' style comments, which can happen when commenting out large blocks.
<?php
/*
echo "This is a test"; /* This comment will cause a problem */
*/
?>