GUID, CLSID

GUID (pronounced goo- id) stands for Globally Unique IDentifier, a 128-bit (16-byte) number generated by an algorithm designed to ensure its uniqueness. This algorithm is part of the Open Software Foundation (OSF) Distributed Computing Environment (DCE), a set of standards for distributed computing.

GUIDs are used to uniquely identify entries in the Windows registry. For example, Visual Basic automatically generates a GUID that identifies your type library in the Windows registry.

Visual Basic also automatically generates a GUID for each public class and interface in your component. These are usually referred to as class IDs (CLSID) and interface IDs (IID). Class IDs and interface IDs are the keys to version compatibility for components authored using Visual Basic.