Typically, you do not need to explicitly register a type library because it is registered automatically when you register your COM server application (see Registering a COM object). However, when you create a type library using the Type Library wizard, it is not associated with a server object. In this case, you can register the type library directly using the toolbar. 

Registering the type library,

• Performs a syntax check
• Adds an entry to the Windows Registry for the type library

To register the type library, choose the Register icon on the Type Library Editor toolbar.