COM Info

Common Object Model is Microsoft's architecture for interchangeable, plugin objects. This is built on existing Microsoft Dynamic Link Library (DLL), Dynamic Data Exchange (DDE) and Object Linking & Embedding (OLE) technologies.

Active X is Microsoft's catch-all name for technologies that leverage COM; it is also driving the way to Distributed COM (DCOM), through new Intenet and Web technologies.

Introduction to COM
COM Overview
Distributed COM (DCOM) Draft

Other References

Grafman's Active X Tips

Microsoft's Active Platform Info Page

Microsoft's COM/DCOM Info Page

Microsoft's COM spec