PHP is a server-side scripting language for web development. It is use to make dynamic and interactive web pages. PHP is an old and well-known technology, but it is still very popular and easy to learn. PHP is open source (free) and cross-platform. Espessially, the combination of PHP and MySQL is a powerful combination used to create rich, dynamic web pages.
PHP Tutorial - www.w3schools.com
Software Development and Enginnering Resources
Database Systems, Structured Query Language