It is hierarchical in nature. It is not hierarchical. Objects are a collection of attributes and the operations that can be performed on thoses attributes. Object is an instance of class. Methods or Services are operations associated with a class.
Encapsulation is the packaging together of the data and operations of a class.
Inheritance is the ability of an object or new class to inherit the attributes of a defined class. Coheision Coheision represents the relationship between a modules internal elements. It stems from information hiding and indicates the single mindedness of a module. High functional cohesion is disired. Coupling Coupling is one of the measures of the functional independence of a software model.