What is PHP?
PHP is a recursive acronym for "PHP Hypertext Preprocessor". It is an open source, interpretive, HTML centric, server side scripting language. PHP is especially suited for Web development and can be embedded into HTML pages
When running server-side, the PHP model can be seen as an alternative to Microsoft's ASP.NET/C#/VB.NET system, Macromedia's ColdFusion, Sun Microsystems' JSP, Zope, mod_perl and the Ruby on Rails framework.
The LAMP (Linux, Apache, MySQL, and PHP) architecture has become popular in the Web industry as a way of deploying inexpensive, reliable, scalable, secure web applications. PHP is commonly used as the P in this bundle alongside Linux, Apache and MySQL. PHP can be used with a large number of relational database management systems, runs on all of the most popular web servers and is available for many different operating systems. This flexibility means that PHP has a wide installation base across the Internet.
Examples of popular server-side PHP applications include phpBB, Wordpress and MediaWiki.
More recently, PHP has been adapted to provide a command line interface, as well as GUI libraries such as GTK+ and text mode libraries like Ncurses and Newt in order to facilitate development of a broader range of software.