PHP / FI 2.0 is an early and no longer supported version of PHP.
PHP/FI 2.0 is an early and no longer supported version of PHP. PHP 3 is the successor to PHP/FI 2.0 and is a lot nicer. PHP 4 is the current generation of PHP, which uses the Zend engine under the hood. PHP 5 uses Zend engine 2 which, among other things, offers many additional OOP features. PHP 5 is experimental.