Automation and Extensibility for Visual Studio
You can extend Visual Studio by using macros, add-ins, VSPackages, and Managed Extensibility Framework (MEF) extensions.
You can use macros and add-ins in Visual Studio without installing the Visual Studio Software Development Kit (SDK).
However, to use VSPackages and the Managed Extensibility Framework, you must install the Visual Studio SDK. For information about how to download the Visual Studio SDK, see Visual Studio Extensibility Developer Center on the MSDN Web site.
For information about how to extend Visual Studio by using the Visual Studio SDK, see Developing Visual Studio Extensions on the MSDN Web site.