PHP Manual . ... The PHP 3.0 Apache module no longer supports Apache versions prior to 1.2. Apache 1.2 or later is required. echo() no longer supports a format string. Use the printf() function instead. ... This is not true for PHP 3.0. Reading arrays with $array[] is no longer supported . ... Use "." instead. ... In PHP 2.0 this would echo 11, in PHP 3.0 it would echo 2. ... This would echo 2 in both PHP 2.0 and 3.0. $a = 1; $b = 1; echo $a.$b; This will echo 11 in PHP 3.0. ...