The member variables of the base classes that are created when you add bookmarks, named ranges, list objects, and so on to Excel are called as host controls in the Excel object model. VSTO has improved a number of objects in the Excel 2007 object model, such as the capability to bind data to an object. You can also expose the object's events. These objects are called Excel host items and Excel host controls. Microsoft .NET-friendly classes, which are built on top of the native Office objects, are meant to be host controls. Some Office developers refer to these controls as the content controls of Excel. These controls provide you with a wide variety of data formatting, and give fine development control to developers, in order to provide better presentation of data for Excel users.
In general, host controls have some basic functionality, as Office objects are based on some enhanced features, such as richer event models and data binding capabilities. The host controls can...