PHP started to become known as what it is today when the parser was rewritten by Zeev Suraski and Andi Gutmans to form PHP Version 3. The rewrite started in 1997, two years after the first public release. Even with the rewrite, the PHP team first released PHP/FI Version 2 on November 1st, 1997. Months later, on June 6th, 1998, PHP Version 3 was officially released to the public.

As if the rewrite of the PHP parser to Version 3 wasn't enough; Zeez Surasky and Andi Gutmans then began to work on the Zend Engine in 1999, which was another rewrite of PHP's core. The first official release of the new rewrite was PHP Version 4.0, with Zend Engine 1.0 on May 22nd, 2000.

PHP Version 4 made it up to 4.4.9, and then became EOL'ed (End of Life); which means as of August 2008, the PHP Version 4 branch is no longer in development nor supported.

PHP Version 5 was released on July 13th, 2004 alogn with Zend Engine 2. PHP 5 was a big rewrite of PHP's core to include improved Object Oriented Programming (OOP) and various performance/security enhancements. PHP Version 5 is currently the stable branch that is being developed, since PHP 4 had been EOL'ed in 2008. As of November 19th, 2009 - the latest release of PHP Version 5 is 5.3.1. PHP Version 5.3 introduced many new features included the long-awaited namespaces, anonymous functions, and late-static binding.