Type Libraries describe most COM objects, including both Automation objects and ActiveX controls. A Type Library can exist in one of the following forms:

• A separate file with the extension .tlb or .olb. This file is usually in the same directory as the main binary file for the Automation Server or ActiveX control.
• Part of the main binary file for the Automation Server or ActiveX control, generally with the extension .exe, .dll, or .ocx. This is often the form provided with ActiveX controls.