PHP is a general purpose scripting language that is well suited for server-side web development. It was created by Rasmus Lerdorf in 1995 and has been developing ever since. PHP originally stand for "Personal Home Page". He used the sets of Perl scripts he called PHP to maintain his resume and keep track of how much traffic his page was getting. He wrote these as "C programming language common gateway interface" which allowed the ability to work with web forms and databases. It also enabled users to start developing dynamic web application. He disclosed and released PHP / FI or "Personal Home Page / Forms Interpreter Version 1.0" in June 8th 1995 to locate bugs and code improvement faster. This release had the functionality that PHP has today. The syntax was similar to Perl but more limiting and simpler.
A development team began to form. They spent months working and beta testing and released PHP / FI 2 in November 1997. Short after, the alphas of PHP 3 were released.
PHP 3.0 syntax to closely resemblance of today's PHP, created by Andi Gutmans and Zeev Suraski in 1997. After finding out that PHP 2.0 was way underpowered for eCommerce application. Andi, Rasmus and Zeev decided to work together and announced PHP 3 as the successor of PHP / FI 2.0 and development of it was stopped soon after. The strength of PHP 3 was strong extensibility features. It also provided end users a solid infrastructure for lots of different databases, protocols and APIs. Another feature was the introduction of object-oriented syntax support. Approximately 10% of web servers on the internet had PHP 3 installed by the end of 1998. PHP 3 was released in June of 1998.
By winter of 1998, Andi and Zeev started working on rewriting the PHP's core. They goals were to improve the performance of complex application and modularity of PHP's code base. This new engine called "Zend Engine", met those goals and was announced in middle of 1999. PHP 4 was based on this engine. Additional features were added and were officially released in May 2000. PHP 4.0 included 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.
Today, PHP is being used by developers all over the world and installed on 20% of domains on the internet. The latest release PHP 5 was released in July 2004 and is driven by the Zend Engine 2.0 with new object model and tons of new features.