Whenever a request comes for a static HTML, the page is returned to the client by the web server without doing the script processing or execution; hence the pages lack the dynamic capability of content fixing. The web server is IIS in Windows and for Linux systems it is the Apache web servers, which are generally used. However PHP and Apache run well in Windows platform also

Now the catch point is in case of PHP pages the server does not return the page directly to the client and instead the web server runs the PHP engine and post backs the output of the executed script to the client’s machine. Pages become dynamic and depending on the various input conditions the page content can be changed dynamically.

As we organize the files and folders the sites are also organized at the server. Usually files with PHP or php3 extensions are files which contain PHP code. Same way we can say that the files with .asp are the active server page files, which contains the asp code. However, this is not always true! At the server settings we can tell the web server which type of files to execute through which engine or scripting language. A file with .htm extension can also pass through the PHP engine in order to execute PHP codes present inside.

Finally, after executing various types of engine, at the user’s browser the final scrip is posted without the scripting language like PHP or ASP and it only contains HTML and oter However after executing different types engines the final script is posted to user browser which does not contain any PHP, ASP or any other types of scripting language and it only contains HTML and other client side scripts.