Some of the characteristics closely related to classes are inheritance, polymorphism and encapsulation, inheritance
Inheritanceøthe specialization relationship is typically implemented using inheritance. Polymorphism (polymorphic): There is the powerful aspects to inheritance. Øone is code reuse. Øthe second is polymorphism (many-forms). A virtual function that is defined in a parent class can be overridden in a subclass. Override is necessary. Limitations of Abstractøabstract does force all the derived classes to implement the method and nothing forces the derive D derived classes to implement its own Drawwindow () method. The Øsealed class (derivation is not allowed at all) to prevent accidental inheritance. Is the opposite of the abstract class (used to derive). A new protected member cannot be created in the Øsealed class.
More about the fourth class of C #