Core PHP is a server-side scripting language for the web. It is very basic PHP, used to create dynamic web pages. It works without any extra library and so it is very important to learn core or principle PHP programming to create dynamic web applications. It helps to understand the logic behind the framework. The logical thinking can be improved with Core PHP. The Core PHP can become bad only when it goes to a bad programmer's desk. Without learning or coding in Core PHP, one should not work on the framework.