Because components are classes, component writers work with objects at a different level from application developers. Creating new components requires that you derive new classes. 

Briefly, there are two main differences between creating components and using them in applications. When creating components,

• You access parts of the class that are inaccessible to application programmers.
• You add new parts (such as properties) to your components.

Because of these differences, you need to be aware of more conventions and think about how application developers will use the components you write.