If you have written applications with Delphi, you know that a class contains both data and code, and that you can manipulate classes at design time and at runtime. In that sense, you've become a component user. 

When you create new components, you deal with classes in ways that application developers never need to. You also try to hide the inner workings of the component from the developers who will use it. By choosing appropriate ancestors for your components, designing interfaces that expose only the properties and methods that developers need, and following the other guidelines in the following topics, you can create versatile, reusable components. 

Before you start creating components, you should be familiar with these topics, which are related to object-oriented programming (OOP):

• Defining new classes
• Ancestors
• Controlling access
• Dispatching methods
• Abstract class members
• Classes and pointers