Sailing stones, also called sliding or moving rocks is a geological phenomenon where rocks tend to move and leave long tracks into a valley surfaces like deserts without human or animal intervention.
Capturing a screen of your iPad into an image can be quite useful sometimes, without that option, making this tutorial would not be as simple as it was.
If you want to start learning PHP and MySql, the first step is to setup complete environment on your local computer. This will include Apache web server with PHP support and MySql database server.