Some developers code their PHP projects writing classes of objects.
Others also write classes but do it just because they see others doing it without being able to explain why classes are a good thing.
Others do not write classes but reuse other people code written in the form of classes.
Others completely refuse to write or reuse other developer classes because they do not see much point in doing it.
Read this article to learn why it is better to develop your PHP projects based on object classes.
You may also learn how to convert your global code based classes into properly written classes that you can reuse in multiple projects besides other benefits of using Object Oriented Programming in PHP.