Virtual functions

What, pray tell, is the purpose of a virtual function? Also, why would you implement a "virtual" method? It just doesn't make sense.

>>1
Hey fucktard, the purpose of a virtual function is a placeholder for classes that derive from it.  Derived classes can implement the function in a way meaningful to the class.  That way you can have a method supported by multiple subclasses.  If you make the virtual function pure, then non-abstract subclasses HAVE to implement it.  Thanks.