COM property pages provide a user interface for setting the properties (or calling the methods) of one or more COM objects. Property pages are used extensively by ActiveX controls for providing rich user interfaces that allow control properties to be set at design time. They can also be used in other areas - for example, the tabbed pages that you see on the ATL Object Wizard dialog box are COM property pages.
Property pages are COM objects that implement the IPropertyPage or IPropertyPage2 interface. These interfaces provide methods that allow the page to be associated with a site (a COM object representing the container of the page) and a number of objects (COM objects whose methods will be called in response to changes made by the user of the property page). The property page container is responsible for calling methods on the property page interface to tell the page when to show or hide its user interface, and when to apply the changes made by the user to the underlying objects.
Each property page can be built completely independently of the objects whose properties can be set. All that a property page needs is to understand a particular interface (or set of interfaces) and to provide a user interface for calling methods on that interface.
For more information, see Property Sheets and Property Pages in the Platform SDK.