What is a CTS?

In order that two different languages can communicate Microsoft introduced Common Type System. For example in VB you have “Integer” and in C++ you have “long” these datatypes are not compatible so the interfacing between them is very complicated.
In order that two language communicate smoothly CLR has CTS (Common Type System).

So “Integer” datatype in VB6 and “int” datatype in C++ will convert it to System.int32 which is datatype of CTS.