First Chapter in PHP tutorials for dummies - What Is PHP?

PHP is a server-side scripting language designed specifically for the Web.Within an HTML page, you can embed PHP code that will be executed each time the page is visited. Your PHP code is interpreted at the web server and generates HTML or other output that the visitor will see.

PHP was conceived in 1994 and was originally the work of one man, Rasmus Lerdorf. It was adopted by other talented people and has gone through four major rewrites to bring us the broad, mature product we see today. As of August 2004, it was installed on more than 17 million domains worldwide, and this number is growing rapidly.

You can see the current number at http://www.php.net/usage.php

Introduction 1
PHP is an Open Source product, which means you have access to the source code and can use, alter, and redistribute it all without charge. PHP originally stood for Personal Home Page but was changed in line with the GNU recursive naming convention (GNU = Gnu’s Not Unix) and now stands for PHP Hypertext Preprocessor.

The current major version of PHP is 5.This version has seen a complete rewrite of the underlying Zend engine and some major improvements to the language. The home page for PHP is available at http://www.php.net/ The home page for Zend Technologies is http://www.zend.com/