The Type Library Importer is a Microsoft tool that converts the type definitions found within a COM type library into equivalent definitions in a common language runtime assembly.
The output of the Type Library Importer (tlbimp.exe) is a binary file (an assembly) that contains runtime metadata for the types defined within the original type library.
COM type definitions usually reside in a type library. In contrast, CLS-compliant compilers produce type metadata in an assembly. The two sources of type information are quite different. The Type Library Importer is used for generating metadata from a type library. The resulting assembly is called an interop assembly, and the type information it contains enables .NET Framework applications to use COM types.
More information is availabe on MSDN, including a guide on how to use it.
