[postlink] https://developmentvideos.blogspot.com/2011/09/httpwww_12.html[/postlink] http://www.youtube.com/watch?v=0I6HbYWFTAAendofvid [starttext] Object-oriented programming languages have built-in support for polymorphic operations within class hierarchies. Inheritance allows a derived class to inherit attributes and methods from another class. Composition means that an object is built from other objects. [endtext]