PHP (short for Hypertext Pre-processor) is one of the most popular scripting languages. PHP code can be embedded within your HTML code. Web pages containg PHP scripts are dinamically pages and ought have the extension ".php".
If a PHP page is accessed, the PHP code is detected, the commands inside of PHP code is executed by the web server and result is transformed into common HTML code which can be read by the browser. Because of this the users can not view the PHP code in the source of the page.
PHP is a powerful tool for making dynamic and interactive web pages. It is used, for example, into an ecommerce web site with product catalogs. It allows you to get and put products information in a database and showing products information on HTML pages.
We have chosen PHP and not another solution for the next reasons:
PHP is free.
PHP runs on Linux, Windows, Unix and other platforms.