Interacting with the User?

Variables can used to stored the data or information that is entered by the user. Like in example, if the textbox with name username on the page, the value entered into the box will available to PHP script  as the variable $username.

PHP Syntax?

PHP syntax is:

<?PHP  -  it is starting tag

?>         -  it is ending tag.

PHP?

PHP stands for Hypertext Preprocessor. PHP is the server side  language. It is used to create the dynamic websites. PHP mostly use with the MySQL. MySQL is a database.
For the PHP it is necessary to install the server (Apache, IIS, etc), PHP and MySQL.
Lets start the working in PHP.