One of the most important factors in dynamic web page development is database definition. If your tables are not set up properly, it can cause you a lot of headaches down the road when you have to perform miraculous SQL calls in your PHP code in order to extract the data you want. By understanding data relationships and the normalization of data, you will be better prepared to begin developing your application in PHP. This 6-page article describes the data relationships and the normalization of data using a simple example.