• PHP is open source language, free to download and free to use. You do not require any license for using PHP language.
• PHP is a scripting language and does not required compilation that's why run quickly.
• PHP is loosely coupled language mean you does not required to declare the data type of variable therefor easy to use and easy to learn.
• Cross platform language and run on all the platform - (Mac, Linux, Window Unix, etc.).
• Compatible with all commonly known databases. MySQL, SQL Server, Oracle, DB2, Access etc.
• Run on all servers - (Apache, IIS, etc. ).
• PHP used widely therefor has very large guide line on internet. There are hundreds of Free PHP Tutorial websites, Free PDF Books, PHP blogs and PHP forums.
• There are hundreds of websites where you can download Free PHP Script, PHP Classes and PHP Modules.
• PHP is the most popular language and more then 224 million [figure from Wikipedia] websites are using the PHP language.
http://www.phpfolder.com/why-php
