what is PHP ?

PHP (Hypertext Processor) is a free, server-side scripting language designed for dynamic websites and app development. It can be directly embedded into an HTML source document rather than an external file, which has made it a popular programming language for web developers. PHP powers more than 200 million websites, including Wordpress, Digg and Facebook.

***Where to learn it:***
Udemy,
Codecademy,
Lynda.com,
Treehouse,
Zend Developer Zone,
PHP.net.