PHP

About PHP

            PHP is a powerful tool for making dynamic and interactive Web pages. PHP stands for PHP Hypertext Preprocessor. It is a server side Technology. PHP Scripts are executed on server. It contains HTML tags and JavaScript.

What is needed?

   you need access to a computer or a server that can run PHP. In contrast to HTML and CSS, PHP is not affected by which browser your visitors use, but by the type of server that's hosting your pages. This is because PHP is a server-side technology.

What is PHP?

PHP was originally an acronym for Personal Home Pages, but is now a recursive acronym for PHP: Hypertext Preprocessor. PHP was originally developed by the Danish Greenlander Rasmus Lerdorf, and was subsequently developed as open source. PHP is not a proper web standard - but an open-source technology. PHP is neither real programming language - but PHP lets you use so-called scripting in your documents.

To describe what a PHP page is, you could say that it is a file with the extension .php that contains a combination of HTML tags and scripts that run on a web server.

How does PHP work?

Explanation

The best way to explain how PHP works is by comparing it with standard HTML. Imagine you type the address of an HTML document (e.g. HTTP://www.mysite.com/page.htm) in the address line of the browser. This way you request an HTML page. It could be illustrated like this:

As you can see, the server simply sends an HTML file to the client. But if you instead type http://www.mysite.com/page.php - and thus request anPHP page - the server is put to work:

The server first reads the PHP file carefully to see if there are any tasks that need to be executed. Only when the server has done what it is supposed to do, the result is then sent to the client. It is important to understand that the client only sees the result of the server's work, not the actual instructions. This means that if you click "view source" on a PHP page, you do not see the PHP codes - only basic HTML tags. Therefore, you cannot see how a PHP page is made by using "view source". You have to learn PHP in other ways, for example, by reading this tutorial.

For more detail, visit the following link:

http://www.w3schools.com/php/php_intro.asp