21⟩ Why COM need GUIDs?
A globally unique identifier (GUID) is used for unique IDs. No two GUIDs are the same no matter what computer they were generated on. The attribute clsid defines the GUID of the associated ActiveX control to use.
“C++ COM ActiveX frequently Asked Questions by expert members with experience in C++ COM ActiveX. These questions and answers will help you strengthen your technical skills, prepare for the new job test and quickly revise the concepts”
A globally unique identifier (GUID) is used for unique IDs. No two GUIDs are the same no matter what computer they were generated on. The attribute clsid defines the GUID of the associated ActiveX control to use.
IUnknown interface provides clients like DirectX control of to get pointers to other interfaces. All COM interfaces are inherited from IUnknown interface. It is used In multiple inheritance where the various interfaces can share one implementation of IUnknown.