Once you know some PHP basics, MySQL is the perfect next step. You can use PHP to interact with MySQL to store information in a logical and secure fashion that can be easily accessed at any time with PHP. Using MySQL you can make your scripts more complex and interactive than if you are trying to store everything in a flat file. [Get Started with MySQL]

The Pythagorean Theorem tells us we can calculate the hypotenuse of a right triangle using the formula a²+b²=c². We can plug this formula into PHP to calculate the hypotenuse, or we can use the hypot () PHP function that does this for us automatically. [Read about Hypotenuse]

As a PHP programmer you are often asked to install scripts on peoples websites. PhpBB is one of the most popular forums available, and one I am asked to install a lot. Many users are still using phpBB2 and are looking to upgrade to phpBB3, but looking over the official install and conversion instructions can be intimidating even to someone who knows a bit of PHP. This tutorial helps break down upgrading from phpBB2 to phpBB3 into simple and easy to understand steps.

PHP works closely with HTML, and can be embedded right into your existing HTML code. If you are not familiar with HTML you should learn the basics before starting PHP. Fortunately you can do that right here at About.com in our Web Design section. Learn HTML.