Beginning ActiveX - Part 1, Page 2
The short answer is a class with a graphical front-end. You may or may not have used classes before, but they are a great way to create code that you can easily reuse in a later project. ActiveX controls take this idea one step further, allowing you to write a widget that you can package and reuse in later applications, or even distribute it as the perfect solution to other budding developers' problems.
With ActiveX, you can make a composite control: one control made up of several others. This means that you can take the ordinary VB controls, or any other ActiveX control for that matter, put them in your ActiveX control, write the functionality that you want, all in one reusable component.