What Is a COM Add-in?This content is no longer actively maintained. It is provided as is, for anyone who may still be using these technologies, with no warranties or claims of accuracy with regard to the most recent product version or service release.
A COM add-in is a dynamic-link library (DLL) that is specially registered for loading by the Microsoft® Office XP applications. You can build COM add-ins with any of the Office applications in Office XP Developer. In addition, you can create COM add-ins with Microsoft® Visual Basic® or Microsoft® Visual C++®. For more information about these tools, see the Microsoft Developer Network (MSDN®) Web site at http://msdn.microsoft.com.
Note A COM add-in also can be a Microsoft® ActiveX® .exe file for Visual Basic. However, DLLs generally provide better performance than .exe files.
COM add-ins use the Component Object Model that makes it possible for you to create a single add-in that is available to one or many of the Office applications — Microsoft® Word, Microsoft® Excel, Microsoft® Access, Microsoft® PowerPoint®, Microsoft® Outlook®, Microsoft® FrontPage®, or even the Visual Basic Editor. By developing COM add-ins, you can extend the functionality of your Office-based applications without adding complexity for users.
Add-ins, Templates, Wizards, and Libraries | COM Add-ins vs. Application-Specific Add-ins | Building COM Add-ins for Office Applications | Building COM Add-ins for the Visual Basic Editor | Building Application-Specific Add-ins | Creating Templates | Creating Wizards | Building Reusable Code Libraries