Benefits of class libraries

• Objects and their corresponding classes break down complex programming problems into many smaller, simpler problems.
• Encapsulation enforces data abstraction: the organization of data into small, independent objects that can communicate with each other. Encapsulation protects the data in an object from accidental damage, but allows other objects to interact with that data by calling the object's member functions.
• Subclassing and inheritance make it possible to extend and modify objects: that is, to derive new kinds of objects from the standard classes available in the system, thereby creating new capabilities without having to start from scratch.
• Polymorphism and multiple inheritance make it possible for different programmers to mix and match characteristics of many different classes and create specialized objects that can still work with related objects in predictable ways.
• Class hierarchies and containment hierarchies provide a flexible mechanism for modeling real-world objects and the relationships among them.