These are technologies we use to develop dynamic websites, PHP is a server side scripting language and MySql is a database tool.
When you look at a website, what you are seeing is the'rendered' HTML. Your browser (Internet Explorer, Firefox, Chrome, etc.) interprets the underlying HTML code and displays it according to a set of rules (which unfortunately can vary between browsers).
On large, dynamic websites which may have hundreds or even thousands of pages, page templates are used. These pages are constructed using PHP. The page content is stored in a Database and extracted using MySql.
There are various tools that do a similar job, we choose to work with PHP & MySql because it's...
For these reasons, PHP & MySql are the most popular development tools for Dynamic Websites.