What is it?
PHP stands for PHP: Hypertext Preprocessor - one of those recursive acronyms like GNU (GNU's Not Unix) which confirm prejudices about geeky humour.
It is an HTML-embedded scripting language, similar in application to Microsoft's Active Server Pages (ASP). It is used to create dynamic Web pages. Unlike ASP, it is an open source product, available free, and supported by a community of developers and users.
Also unlike ASP, which requires the full infrastructure of Microsoft technology, PHP is platform-independent.
Until recently it was most associated with Apache and Linux but it is now being taken up by Microsoft users.
Where did it originate?
PHP was created in 1994 by Rasmus Lerdorf to keep track of who was looking at his online CV. He called it Personal Home Page tools. Like Linux, PHP was taken up by an enthusiastic community of open source users, who added their own code to it. Originally based on another scripting language, Perl , PHP includes syntax borrowed from Java and C.
In 1997 it was completely rewritten by Andi Gutmans and Zeev Suraski. With Lerdorf's co-operation, this commercially robust version was released as PHP3.
The current version, PHP4, has improved modularity, support for a wider range of databases, and better performance when handling complex applications. PHP4 and the forthcoming PHP5 are built on the Zend "engine" created by Gutmans and Suraski.
What is it for?
At its simplest, you add embedded code to HTML to do the dynamic stuff on your Web pages. Originally devised as a forms interpreter (it used to be called PHP/FI), PHP can collect data from Web page users or retrieve and modify data in databases and on other Web pages.
What makes it special?
PHP resides on the server, and can be used by all current Web browsers, making it completely transparent to users.
Because PHP was redesigned from the ground up as a scripting language, it contains a lot of pre-built functionality to make life easier for developers. Champions claim it creates faster, shorter, more efficient code than ASP.
It is compatible with about 20 different databases and is particularly closely integrated with the rising star among open source databases, MySQL.
How difficult is it?
Developers with a working knowledge of HTML and either C, Java or Perl should pick it up easily.
Where is it used?
The official PHP Web site ( www.php.net/) claims more than three million Web sites use it. It is shipped with Linux distributions such as Red Hat, and the Apache Web server. You can buy it as an Apache/MySQL/PHP bundle (Foxserv) or an integrated development environment (Nusphere PHPEd).
What does it run on?
Unix and Linux variants, all versions of Windows, MacOS, Netware, and minority-interest operating systems such as OS/2 and AmigaOS.
Not to be confused with
A designer drug favoured by clubbers; an academic qualification you can buy from the University of Spam.
Few people know that
The name "Zend" was created from the forenames of its founders, Zeev and Andi.
What is coming up?
PHP5, due for release in the summer, will provide better performance and a more complete object-oriented programming environment, enabling it to front-end J2EE and .net applications more effectively.
You can download PHP4 from the official PHP Web site at www.php.net/ or from the Zend Web site at www.zend.com/. Downloadable manuals can also be found on these sites, along with tutorials and lists of links to PHP scripts and training resources.
Web developers with PHP skills can expect to earn between £23,000 and £35,000 per annum.