Appendix A. History of PHP and related projects

Table of Contents
History of PHP
History of PHP related projects
Books about PHP
Publications about PHP

PHP has come a long way in the last few years. Growing to be one of the most prominent languages powering the Web was not an easy task. Those of you interested in briefly seeing how PHP grew out to what it is today, read on.

History of PHP

PHP 3

PHP 3.0 was the first version that closely resembles PHP as we know it today. It was created by Andi Gutmans and Zeev Suraski in 1997 as a complete rewrite, after they found PHP/FI 2.0 severely underpowered for developing their own eCommerce application. In an effort to cooperate and start building upon PHP/FI's existing user-base, Andi, Rasmus and Zeev decided to cooperate and announce PHP 3.0 as the official successor of PHP/FI 2.0, and development of PHP/FI 2.0 was mostly halted.

One of the biggest strengths of PHP 3.0 was its strong extensibility features. In addition to providing end users with a solid infrastructure for lots of different databases, protocols and APIs, PHP 3.0's extensibility features attracted dozens of developers to join in and submit new extension modules. Arguably, this was the key to PHP 3.0's tremendous success. Other key features introduced in PHP 3.0 were the object oriented syntax support and the much more powerful and consistent language syntax.

The whole new language was released under a new name, that removed the implication of limited personal use that the PHP/FI 2.0 name held. It was named plain 'PHP', with the meaning being a recursive acronym - PHP: Hypertext Preprocessor.

By the end of 1998, PHP grew to an install base of tens of thousands of users (estimated) and hundreds of thousands of Web sites reporting it installed. At its peak, PHP 3.0 was installed on approximately 10% of the Web servers on the Internet.

PHP 3.0 was officially released in June 1998, after having spent about 9 months in public testing.

PHP 4

By the winter of 1998, shortly after PHP 3.0 was officially released, Andi Gutmans and Zeev Suraski had begun working on a rewrite of PHP's core. The design goals were to improve performance of complex applications, and improve the modularity of PHP's code base. Such applications were made possible by PHP 3.0's new features and support for a wide variety of third party databases and APIs, but PHP 3.0 was not designed to handle such complex applications efficiently.

The new engine, dubbed 'Zend Engine' (comprised of their first names, Zeev and Andi), met these design goals successfully, and was first introduced in mid 1999. PHP 4.0, based on this engine, and coupled with a wide range of additional new features, was officially released in May 2000, almost two years after its predecessor, PHP 3.0. In addition to the highly improved performance of this version, PHP 4.0 included other key features such as support for many more Web servers, HTTP sessions, output buffering, more secure ways of handling user input and several new language constructs.

PHP 4 is currently the latest released version of PHP. Work has already begun on modifying and improving the Zend Engine to integrate the features which were designed for PHP 5.0.

Today, PHP is being used by hundreds of thousands of developers (estimated), and several million sites report as having it installed, which accounts for over 20% of the domains on the Internet.

PHP's development team includes dozens of developers, as well as dozens others working on PHP-related projects such as PEAR and the documentation project.