Open Object Rexx includes features typical of an object-oriented language-features like data encapsulation, inheritance and polymorphism. Open Object Rexx is an extension of the traditional Rexx language, which has been expanded to include objects, classes and methods. These extensions do not replace traditional Rexx functions, or preclude the development or running of traditional Rexx programs. You can program as before, program with objects, or mix objects with regular Rexx instructions. The Rexx programming concepts that support the object-oriented features are described in this chapter.