The HKEY CLASSES ROOT Key

The HKEY_CLASSES_ROOT Key

The HKEY_CLASSES_ROOT root key contains information on all existing filename associations and data associated with COM objects. As I mentioned earlier, these data are the same as that contained under the Classes subkey of the HKEY_LOCAL_MACHINE\Software hive.

The only purpose for the HKEY_CLASSES_ROOT registry root key is to provide backward compatibility with the Windows 3.1x registry database.

The HKEY_CLASSES_ROOT key contains the data that associates file types (by filename extensions) with specific applications supporting formats of these files.