Some of the content in this topic may not be
applicable to some languages.
Add-ins are programs that add optional commands and features to Microsoft Excel. For example, the Analysis ToolPak add-in program (add-in: A supplemental program that adds custom commands or custom features to Microsoft Office.) provides a set of data analysis tools that can save steps when you develop complex statistical or engineering analyses.
Excel has three types of add-in programs: Excel add-ins, custom Component Object Model (COM) add-ins (COM add-in: A supplemental program that extends the capabilities of a Microsoft Office program by adding custom commands and specialized features. COM add-ins can run in one or more Office programs. COM add-ins use the file name extension .dll or .exe.), and automation add-ins.
Excel add-ins
Where to get add-ins A set of add-ins is available when you install Excel, and more add-ins are available from the Microsoft Office Web site.
Installing add-ins on your computer Before you can use an add-in, you must first install it on your computer and then load it into Excel. Add-ins (*.xla files) are installed by default in one of the following places:
The administrator for your company's network can designate other locations for add-in programs. See your administrator for more information.
Loading add-ins into Excel After installing an add-in, you must load it into Excel. Loading an add-in makes the feature available in Excel and adds any associated commands to the appropriate menus.
Unloading add-ins from Excel To conserve memory and improve performance, unload add-ins you don't use often. Unloading an add-in removes its features and commands from Excel, but the add-in program remains on your computer so you can easily reload it. When you unload an add-in program, it remains in memory until you restart Excel.
Designing custom Excel add-ins You can use your own Visual Basic (Visual Basic: A high-level, visual-programming version of Basic. Visual Basic was developed by Microsoft for building Windows-based applications.) programs as custom add-ins. For information about making a Visual Basic program an add-in, see the Microsoft Office XP Developer's Guide, which you can obtain from Microsoft.
COM add-ins
COM add-ins are supplemental programs that provide additional functionality in a variety of programming languages, including Visual Basic (Visual Basic: A high-level, visual-programming version of Basic. Visual Basic was developed by Microsoft for building Windows-based applications.), Visual C++, and Visual J++.
Using COM add-ins The developer of a COM add-in usually provides installation and removal programs for the add-in. Contact the person who provided the add-in to you for instructions on how to install and use it.
Designing COM add-ins If you are a developer, you'll find information about designing COM add-ins in Visual Basic Help (Microsoft Visual Basic Help: To get help for Visual Basic in Excel, point to Macro on the Toolsmenu, and then click Visual Basic Editor. On the Help menu, click Microsoft Visual Basic Help.). While you are developing and testing, you can load or unload a COM add-in in Excel before you have a working installation program for your add-in.
Automation add-ins
Automation add-ins allow COM automation functions to be called from a worksheet.
Using automation add-ins The developer of an automation add-in usually provides installation and removal programs for the add-in. Contact the person who provided the add-in to you for instructions on how to install and use it. Automation add-ins that have been registered on the system can be accessed through the Tools menu.