its an open source software so tat we can download it free of cost.
the php programming is done in the service side scripting..
and before php we should learn html/xhtml [ html and xhtml are almost similar and have a little differnce] html is basics of a webdesigner.
and also we should know css[cascading style sheets ] it deals with the design of the websites and layouts.
** then we should come to javascript.
java script is the client side scripting. By using client side scripting the loading of the requests in the server will become very less due to javascript.
after learning all this 3 languages, html/xhtml, css , javascript then learn php beacause it ll be very easy and u can learn fastly
**the main advantages of the php is we can connect with the databases.
** and php is loosely packed and also operating system independent it means we can work php and so tat we can work on any operation system.