Add-ins are additions to existing application programs that extend them with certain functions.
Add-ins are macros with special program functions. The term add-in is often used in combination with Microsoft application and utility programs. For example, for add-ins from the Office package. Such add-ins are not part of the standard installation.
Such add-ins can support file export and import, convert or filterfiles. Add-ins are supplied by the software company but also by third parties. Under Windows, add-ins are increasingly used for Object Linking and Embedding (OLE).