COM and the Registry

COM uses the registry to make connections between interface and class ID GUIDs and the components they represent. The HKEY_CLASSES_ROOT key has all the class data. This key is actually an alias for HKEY_LOCAL_MACHINE­\SOFTWARE\Classes, but COM needs the data so often that it’s easier to keep a more specific root key for it. To get some idea of how it all fits together, let’s look at the registry entries for a familiar component, SieveBasExeN.