Standard headers from the STL for C, the headers like iostream.h have .h
They are not part of the C++ language though
The headers form the STL for C++ have the same name as the C headers, just without the .h to allow interoperability.

Yes I have vector in there, otherwise the compile error would have been drastically different and there would not have been a reference to vector.h
Whose inclusion is because I've included <vector>

It's included in the stdafx.h header file, included into this file.