PHP Manual . ... Next . PHP supports 'C', 'C++' and Unix shell-style comments. ... 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 ?> ... 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 */ */ ?> ...