Namespace: System.Runtime.CompilerServices Why we need Interoperation? A company may have a large application that is already tested, verified, and is stable. And they are interested to use new technology while keeping the old at its position. Secondly, not every windows API has been wrapped in with .NET Framework. .Net provides ample support for COM interoperation to import and use type libraries. Runtime Callable Wrapper (RCW) is used to bridge the communication between the COM and .NET. Importing Type Libraries: There are two ways to Import libraries. 1. Using Add Reference Feature in Visual Studio 2005 and selecting appropriate COM component. 2. Using tlbimp.exe . In command prompt go to the location where your assembly is, then execute the command “ tlbimp.exe MyDll.dll [/out:ManagedMyDll.dll] In C# optional parameters are not supported , so if you want to pass somethi...