PHP, short for "PHP: Hypertext Preprocessor", is
an open-source, reflective programming language used mainly for
developing server-side applications and dynamic web content, and
more recently, other software.
PHP allows interaction with a large number of relational database
management systems, such as MySQL, Oracle, IBM DB2, Microsoft SQL
Server, PostgreSQL and SQLite. PHP runs on most major operating
systems, including UNIX, Linux, Windows, and Mac OS X, and can
interact with many major web servers. The official PHP website
contains extensive documentation.
There is a command line interface, as well as GUI libraries such as
the Gimp Tool Kit (GTK+) and text mode libraries like Ncurses and
Newt.
PHP is the result of the efforts of many contributors. It is
licensed under the PHP License, a BSD-style license. Since version
4, it has been powered by the Zend engine.
for more infor, refer to wiki
Official PHP
website