PHP is a server-side scripting language, designed for web development and also as a general-purpose programming language.
The language was created by Rasmus Lerdorf in 1994. He was the one that wrote the original Common Gateway Interface (CGI) component. Together with Andi Gutmans and Zeev Suraski, they rewrote the parser that then created PHP 3.
The development of the programming language began in 1995 when Lerdorf wrote several CGI programs in C, in which he used it to maintain his personal websites. But then he extended it to include web forms and also the ability to communicate with databases.
Lerdorf called this implementation "Personal Home Page/Forms Interpreter" or PHP/FI, something that could help build simple but dynamic web applications.
In order to 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 on June 8, 1995.
That date, is later known as the moment when PHP first appeared to public.
PHP is a general-purpose scripting language that is designed to run on a server-side environment. This is why PHP generally runs on a web server.
The language is flexible as it can be deployed on most web servers, running at many operating systems and platforms, and can be used with many relational database management systems (RDBMS).
For PHP to work, any of its code in a requested file needs to be executed by the PHP runtime. This is usually to create dynamic web page content or dynamic images used on websites or others. PHP can also be used for command-line scripting and client-side graphical user interface (GUI) applications.
Usually, PHP acts as a filter to takes input from a file or stream that contain text and/or PHP codes. Running in the serer, the most common output for PHP is HTML. Others include JSON, XML or others.
PHP is often compared to other similar server-side scripting languages, such as Microsoft's Classic ASP, Sun Microsystems' JavaServer Pages, and mod_perl.
