PHP is a general-purpose scripting language that is used in creating Web pages, and can be embedded in HTML code. (PHP stands for “Hypertext Preprocessor,” even though the acronym doesn’t match up exactly.)
PHP is an open-source program, which means it’s available for free on the Web. PHP can also be used across many platforms, such as Linux, many variations of the Unix system, Mac OS X and Microsoft Windows.
PHP is a complete programming language and can be used for functions such as server-side scripting (using a web server to fulfill a user’s request by running a script directly on the web server to generate dynamic HTML pages) or writing desktop applications.
PHP development began in 1994 when Rasmus Lerdorf wrote several Common Gateway Interface (CGI) programs in C, which he used to maintain his personal homepage. He extended them to work with web forms and to communicate with databases, and called this implementation “Personal Home Page/Forms Interpreter” or PHP/FI.
PHP/FI could be used to build simple, dynamic web applications. To accelerate bug reporting and improve the code, Lerdorf initially announced the release of PHP/FI as “Personal Home Page Tools (PHP Tools) version 1.0” on the Usenet discussion group comp.infosystems.www.authoring.cgi on June 8, 1995.
This release already had the basic functionality that PHP has today. This included Perl-like variables, form handling, and the ability to embed HTML. The syntax resembled that of Perl, but was simpler, more limited and less consistent.
Early PHP was not intended to be a new programming language, and grew organically, with Lerdorf noting in retrospect: “I don’t know how to stop it, there was never any intent to write a programming language.
I have absolutely no idea how to write a programming language, I just kept adding the next logical step on the way.” A development team began to form and, after months of work and beta testing, officially released PHP/FI 2 in November 1997.
The fact that PHP was not originally designed, but instead was developed organically has led to inconsistent naming of functions and inconsistent ordering of their parameters.In some cases, the function names were chosen to match the lower-level libraries which PHP was “wrapping”,while in some very early versions of PHP the length of the function names was used internally as a hash function, so names were chosen to improve the distribution of hash values.
Two programmers, Zeev Suraski and Andi Gutmans, rebuilt PHP’s core, releasing the updated result as PHP/FI 2 in 1997. The acronym was formally changed to PHP: HyperText Preprocessor, at this time. (This is an example of a recursive acronym: where the acronym itself is in its own definition.) In 1998, PHP 3 was released, which was the first widely used version.
PHP 4 was released in May 2000, with a new core, known as the Zend Engine 1.0. PHP 4 featured improved speed and reliability over PHP 3. In terms of features, PHP 4 added references, the Boolean type, COM support on Windows, output buffering, many new array functions, expanded object-oriented programming, inclusion of the PCRE library, and more.
Maintenance releases of PHP 4 are still available, primarily for security updates.PHP 5 was released in July 2004, with the updated Zend Engine.
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