PHP is used mainly in server-side scripting, but can be used from a command line interface or in standalone graphical applications. Textual User Interfaces can also be created using ncurses.The most recent version of PHP is 5.2.5, released on 8 November 2007. It is considered to be free software by the Free Software Foundation.
PHP is a widely-used general-purpose scripting language that is especially suited for Web development and can be embedded into HTML. PHP generally runs on a web server, taking PHP code as its input and creating Web pages as output. However, it can also be used for command-line scripting and client-side GUI applications. PHP can be deployed on most web servers and on almost every operating system and platform free of charge. The PHP Group also provides the complete source code for users to build, customize and extend for their own use.
PHP primarily acts as a filter. The PHP program takes input from a file or stream containing text and special PHP instructions and outputs another stream of data for display.
SERVER- SIDE SCRIPTING
Originally designed to create dynamic web pages, PHP’s principal focus is server-side scripting. While running the PHP parser with a web server and web browser, the PHP model can be compared to other server-side scripting languages such as Microsoft‘s ASP.NET system, Sun Microsystems‘ JavaServer Pages, and mod perl as they all provide dynamic content to the client from a web server. To more directly compete with the “framework” approach taken by these systems, Zend is working on the Zend Framework – an emerging (as of June 2006) set of PHP building blocks and best practices; other PHP frameworks along the same lines include CakePHP, PRADO and Symfony.
The LAMP 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, although the P can also refer to Python or Perl. 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; As of April 2007, over 20 million Internet domains were hosted on servers with PHP installed. The number of installations is different from the number of sites actually using those installations, but this statistic does reflect the popularity of PHP.
PHP also provides a command line interface SAPI for developing shell and desktop applications, daemons, log parsing, or other system administration tasks that have traditionally been the domain of Perl, Python, awk, or shell scripting.
CLIENT-SIDE GUI APPLICATIONS
PHP provides bindings to GUI libraries such as GTK+ (with PHP-GTK), Qt with PHP-Qt and text mode libraries like ncurses in order to facilitate development of a broader range of cross-platform GUI applications.
Wikipedia, 12 de febrero de 2008. Fecha de consulta 12 de febrero de 2008.