Evolution Of PHP

A History of PHP

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.)

What does PHP do?

PHP is a general purpose language. It is normally put to use as an html-embedded scripting language for use on the web, but it can also be used as a shell scripting language or even as a language to write windowed applications, in the form of PHP-GTK.

Due to PHP's open-source nature, if there is something you can't currently do in PHP itself there is nothing stopping you from writing a PHP module or extension in C code to extend its functionality so that you can do what you want from within PHP itself. This is made possible through the well-documented API which is available to all.

PHP4 has two main parts to it:

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The Zend Engine

is the part of the PHP package that keeps track of the requests, processes scripting files, and handles variables and resources. Its homepage can be found at http://www.zend.com/.
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PHP

implements 90% of the functionality seen by the end user. It provides a wide range of modules such as MySQL, ODBC and XML support.