IUnknown

The published [http://www.microsoft.com/com/resources/comdocs.asp COM specification] mandates that Component Object Model objects must minimally implement the IUnknown interface. This interface is comprised of three functions - QueryInterface, AddRef and Release.

QueryInterface is used to retrieve a pointer to a vector containing pointers to object methods AddRef is used by clients to indicate that a COM object is being referenced. This is necessary to ensure that a COM object is not disposed prematurely Release is used by clients to indicate that they have finished using the COM object. An unreferenced COM object may be safely disposed

The IUnknown interface is defined as a GUID with the value of {00000000-0000-0000-C0000-00000000046}.