The Extensibility projects templates in the New Project dialog box enable you to create Add-ins, which are extensions of the Visual Studio integrated development environment (IDE).
You can create two types of add-ins:
Visual Studio Add-ins — A Visual Studio add-in works only in the Visual Studio and Visual Studio Macros environments.
Shared Add-Ins — In addition to working in the Visual Studio and Visual Studio Macros environments, a shared Add-in also works in Microsoft Office applications, such as Microsoft Word, Microsoft Visio, and Microsoft Excel.
To open the New Project dialog box:
On the File menu, point to New, and then click Project.
Expand Other Project Types and click Extensibility.
The Add-in project templates appear in the Templates pane.
Selecting either project starts the Add-In Wizard where you can select:
The programming language in which to create the Add-in.
The application hosts, such as Visual Studio or Microsoft Access.
Other Add-in options.
The Extensibility project templates create a project in the solution and a setup project for distributing the Add-in.