What Is an Add-In?
One of Excel's most useful features for developers is the capability to create add-ins. Creating add-ins adds a professional touch to your work, and add-ins offer several key advantages over standard workbook files.
Generally speaking, a spreadsheet add-in is something added to a spreadsheet application to give it additional functionality. Excel ships with several add-ins. Examples include the Analysis ToolPak (which adds statistical and analysis capabilities) and Solver (which performs advanced optimization calculations).
Some add-ins also provide new worksheet functions that you can use in formulas. With a well-designed add-in, the new features blend in well with the original interface, so they appear to be part of Excel.
Comparing an add-in with a standard workbook
Any knowledgeable Excel user can create an add-in from an Excel workbook file; no additional software or programming tools are required. You can convert any workbook file to an add-in, but not every workbook is appropriate for an add-in. An Excel add-in is basically a normal XLSM workbook with the following differences:
IsAddinproperty of the
True. By default, this property is