One question we haven't really considered to this point is the effect of predefined interfaces on your managed component development. A predefined interface is one in which the interface is already defined and in use. For example, IUnknown is the predefined interface that every COM component supports.
We'll discuss the implications of predefined interfaces on development in this chapter. You'll learn why they're important and what you can do to create them in a managed component. This chapter will also show you some of the tools you have at your disposal for working with predefined interfaces. For example, we'll discuss the OLE/COM Object Viewer-an essential tool for discovering the intricacies of predefined interfaces.
The final sections of this chapter will show how to work with predefined interfaces in your components . You'll find that working with predefined interfaces, even those you have to discover by using documentation and other sources, is easy once you break the problem into manageable pieces.