About COM add-ins
Component Object Model (COM) add-ins are supplemental programs that extend the capabilities of an application by adding custom commands and specialized features that can accommodate specific tasks. For example, a COM add-in created for MapPoint might take a Pushpin set with customer address information, calculate the most efficient route to make deliveries to those customers, and then automatically print a route map with directions.
Developers can design COM add-ins to be loaded and run in MapPoint, implementing them in any Microsoft programming product (such as Microsoft Office, Microsoft Visual Basic, Microsoft Visual C++, and Microsoft Visual J++) or third-party programming product that can create COM DLLs (dynamic-link libraries) and executable files. Users can then simply add, remove, load, and unload the COM add-ins as needed.