PHP has come a long way in the last few years. Growing
to be one of the most prominent languages powering the Web
was not an easy task. Those of you interested in briefly
seeing how PHP grew out to what it is today, read on.
PHP succeeds an older product, named PHP/FI. PHP/FI
was created by Rasmus Lerdorf in 1995, initially as a
simple set of Perl scripts for tracking accesses to his
online resume. He named this set of scripts 'Personal
Home Page Tools'. As more functionality was required,
Rasmus wrote a much larger C implementation, which was
able to communicate with databases, and enabled users to
develop simple dynamic Web applications. Rasmus chose to
release the source code for PHP/FI for everybody to see,
so that anybody can use it, as well as fix bugs in it and
improve the code.
PHP/FI, which stood for Personal Home Page / Forms
Interpreter, included some of the basic functionality of
PHP as we know it today. It had Perl-like variables,
automatic interpretation of form variables and HTML
embedded syntax. The syntax itself was similar to that of
Perl, albeit much more limited, simple, and somewhat
inconsistent.
By 1997, PHP/FI 2.0, the second write-up of the C
implementation, had a cult of several thousand users
around the world (estimated), with approximately 50,000
domains reporting as having it installed, accounting for
about 1% of the domains on the Internet. While there were
several people contributing bits of code to this project,
it was still at large a one-man project.
PHP/FI 2.0 was officially released only in November
1997, after spending most of its life in beta releases.
It was shortly afterwards succeeded by the first alphas
of PHP 3.0.
PHP 3.0 was the first version that closely resembles
PHP as we know it today. It was created by Andi Gutmans
and Zeev Suraski in 1997 as a complete rewrite, after
they found PHP/FI 2.0 severely underpowered for
developing an eCommerce application they were working on
for a University project. In an effort to cooperate and
start building upon PHP/FI's existing user-base, Andi,
Rasmus and Zeev decided to cooperate and announce PHP 3.0
as the official successor of PHP/FI 2.0, and development
of PHP/FI 2.0 was mostly halted.
One of the biggest strengths of PHP 3.0 was its
strong extensibility features. In addition to providing
end users with a solid infrastructure for lots of
different databases, protocols and APIs, PHP 3.0's
extensibility features attracted dozens of developers to
join in and submit new extension modules. Arguably, this
was the key to PHP 3.0's tremendous success. Other key
features introduced in PHP 3.0 were the object oriented
syntax support and the much more powerful and consistent
language syntax.
The whole new language was released under a new
name, that removed the implication of limited personal
use that the PHP/FI 2.0 name held. It was named plain
'PHP', with the meaning being a recursive acronym - PHP:
Hypertext Preprocessor.
By the end of 1998, PHP grew to an install base of
tens of thousands of users (estimated) and hundreds of
thousands of Web sites reporting it installed. At its
peak, PHP 3.0 was installed on approximately 10% of the
Web servers on the Internet.
PHP 3.0 was officially released in June 1998, after
having spent about 9 months in public testing.
By the winter of 1998, shortly after PHP 3.0 was
officially released, Andi Gutmans and Zeev Suraski had
begun working on a rewrite of PHP's core. The design
goals were to improve performance of complex
applications, and improve the modularity of PHP's code
base. Such applications were made possible by PHP 3.0's
new features and support for a wide variety of third
party databases and APIs, but PHP 3.0 was not designed to
handle such complex applications efficiently.
The new engine, dubbed 'Zend Engine' (comprised of
their first names, Zeev and Andi), met these design goals
successfully, and was first introduced in mid 1999. PHP
4.0, based on this engine, and coupled with a wide range
of additional new features, was officially released in
May 2000, almost two years after its predecessor, PHP
3.0. In addition to the highly improved performance of
this version, PHP 4.0 included other key 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.
PHP 4 is currently the latest released version of
PHP. Work has already begun on modifying and improving
the Zend Engine to integrate the features which were
designed for PHP 5.0.
Today, PHP is being used by hundreds of thousands of
developers (estimated), and several million sites report
as having it installed, which accounts for over 20% of
the domains on the Internet.
PHP's development team includes dozens of
developers, as well as dozens others working on
PHP-related projects such as PEAR and the documentation
project.
The future of PHP is mainly driven by it's core, the
Zend Engine. PHP 5 will include the new Zend Engine 2.0.
To get more information on this engine, see
it's webpage.