MinGW ("Minimalistic GNU for Windows") refers to a set of runtime headers, used in building a compiler system based on the GNU GCC and binutils projects. It compiles and links code to be run on Win32 platforms... providing C, C++ and Fortran compilers plus other related tools. If you see references to "mingw32" instead of "MinGW", they are referring to the same compiler system. The project's name changed from mingw32 to MinGW is to prevent the implication that MinGW will only works on 32 bit systems (as 64 and higher bit machines become more common, MinGW will evolve to work with them). MinGW uses the Microsoft runtime libraries, distributed with the Windows operating system.