PHP (Hypertext Preprocessor) is a widely-used open source general-purpose scripting language that is especially suited for web development and it can be embedded into HTML. PHP code can be interspersed with HTML, making it simple to generate dynamic pieces of Web pages.
PHP takes most of its syntax from C, Java, and Perl programming languages. It is an open source technology and runs on all most operating systems and with all most Web servers. PHP was written in the C programming language by Rasmus Lerdorf in 1994 for use in monitoring his online resume and related personal information. Because of this reason, PHP originally stood for “Personal Home Page”. Lerdorf combined PHP with his own Form Interpreter, releasing the combination publicly as PHP/FI (generally referred to as PHP 2.0) on June 8, 1995.
PHP/FI 2
Rasmus came with PHP/FI 2 in 1997, but at that time the development was solely by Rasmus. After its release in November 1997, Andi Gutmans and Zeev Suraski bumped into PHP/FI while looking for a language to develop an e-commerce solution for a university project. They discovered that PHP/FI language was lacking many common features. One of the most interesting features while loops were implemented.
PHP 3
Zeev and Andi decided to completely rewrite the PHP scripting language. They then teamed up with Rasmus to release PHP 3, and along also came a new name: PHP: Hypertext Preprocessor, to emphasize that PHP was a different product and not only suitable for personal use. Zeev and Andi had also designed and implemented a new extension API. This new API made it possible to easily support additional extensions for performing tasks such as accessing databases, spell checkers and other technologies, which attracted many developers who were not part of the “core” group to join and contribute to the PHP project. At the time of PHP 3’s release in June 1998, the estimated PHP installed nearly 50,000 domains. PHP 3 sparked the beginning of PHP’s real php world, and was the first version to have an installed base of more than one million domains, this is the new revolution of php in the scripting languages.
PHP 4
PHP 4 was officially released on May 22, 2002, and today its installed base has surpassed 15 million domains.
PHP 4 came with a new features of “compile first, execute later.” The compilation step does not compile PHP scripts into machine code; it instead compiles them into byte code, which is then executed by the PHP Zend Engine (Zend stands for Zeev & Andi).
After that PHP 4.1.0, which introduced superglobals variables such as $_GET and $_POST $_REQUEST etc. superglobals variables can be accessed from within functions without using the global keyword.
PHP 5
After some time, the demand of php user or developers for more common object-oriented features increased immensely, and Andi came up with the idea of rewriting the objected-oriented part of the Zend Engine. Zeev and Andi wrote the “Zend Engine II: Feature Overview and Design”. this is the biggest change in PHP 5.
Such common features implemented into PHP5 – namespaces and multiple inheritance, which were mentioned in the original document, never made it into PHP 5. Multiple inheritance was dropped in favor of interfaces, and namespaces were dropped completely.