Translations:Developers/Object oriented programming in PHP/Classes/9/en

Generic functionality common to many different classes is provided by superclasses. This way specialised subclasses need not to reimplement already existing methods, they just define the new and special methods and inherite all common functionality by extending the proper superclass. Another advantage is, that the content of common methods can be easily changed by editing the superclasses, all subclasses can be left as they are.