What is PHP? What is it used for?
PHP, as stated on its website ( php.net ) is a very widespread general purpose programming language, which is suitable for programming web applications and can be inserted in HTML.
It is a programming language specifically for manufacturing dynamic pages, pages that can be modified from the administrator online or differentiate, depending on the user's characteristics, for example, operating system, IP address etc.
It is not used for the aesthetic configuration of a page, but for the treatment of the features and the work that will handle. Therefore, the code written for a website in PHP language is not immediately understood but only after the operation of the user on the website.
To understand this: PHP is widely used for web handling capabilities such as user registration, the fora etc. It works with the help of HTML and now with the XHTML (new revised version of HTML).
In combination with the MySQL it can be perfectly used for the Data Management in database. For example, a Web page that the user registration is necessary, PHP can store names and passwords in a database.