Cython is not actually a compiler. It is essentially a more convenient way of writing C/C++ extension modules. It produces C/C++ glue code which is then compile

Cython is not actually a compiler. It is essentially a more convenient way of writing C/C++ extension modules. It produces C/C++ glue code which is then compiled by an actual compiler like gcc. By tapping into the existing C API of cpython it is simpler than PyPy & NumPy which work on a lower level, but on the other hand Cython does little optimization for you.