PHP started life and is still primarily used as a server-side HTML-embedded scripting language.

PHP, known originally as Personal Home Pages, was first conceived in the autumn of 1994 by Rasmus Lerdorf. He wrote it as a way to track visitors to his online CV. The first version was released in early 1995, by which time Rasmus had found that by making the project open-source, people would fix his bugs. The first version was very straightforward and had a simple parser which recognised a few special macros and provided some of the utilities which were in common usage on homepages back then.

The parser was rewritten in mid-1995 and renamed PHP/FI version 2. The "FI" in this version stood for the Form Interpreter which Rasmus had added to PHP to cope with the growing needs of webpages. mSQL support was also added at this time. PHP/FI underwent massive growth, and other people started to contribute code to it regularly.

In mid-1997 Zeev Suraski and Andi Gutmans rewrote the main parser, and PHP shifted from being Rasmus' own to a more group orientated project. This formed the basis for PHP3, now named PHP: Hypertext Preprocessor - a recursive acronym.

The latest version, PHP4, is another rewrite by Suraski and Gutmans and is based around the Zend engine. PHP now has over two hundred regular contributors working on various parts of the project. It has a massive amount of third party extension modules, supports all popular servers natively, and has inbuilt MySql and ODBC support.

The latest statistics show that PHP is now in use on over 5.5 million domains, and has had a steady usage growth rate over the past year. It is far and away the single most popular Apache module; to give this some perspective, Apache currently holds nearly 60% of the market share of Internet webservers, whereas IIS servers (natively supporting ASP) hold less than half that proportion of the market. (Figures taken from http://www.securityspace.com/ March 2001.)