A CLSID is a globally unique identifier that identifies a COM class object. If your server or container allows linking to its embedded objects, you need to register a CLSID for each supported class of objects.
Associates a ProgID with a CLSID. This value is used to determine the latest version of an object application.
Remarks
The HKEY_LOCAL_MACHINE\SOFTWARE\Classes key corresponds to the HKEY_CLASSES_ROOT key, which was retained for compatibility with earlier versions of COM.
The CLSID key contains information used by the default COM handler to return information about a class when it is in the running state.
To obtain a CLSID for your application, you can use the Uuidgen.exe, or use the CoCreateGuid function.
The CLSID is a 128-bit number, in hex, within a pair of curly braces.
The subkeys and registry values associated with the HKEY\_LOCAL\_MACHINE\\SOFTWARE\\Classes key contain information about an application that is needed to support COM functionality.