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. Old PHP releases
can be found at the
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
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
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
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
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.
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
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.
PHP 5 was released in July 2004 after long development and several
pre-releases. It is mainly driven by its core, the Zend Engine 2.0 with a
new object model and dozens of other new features. To get more information
on this engine, see its webpage.