Python has seen wide adoption across industries and disciplines by dint of being easy to work with. But it has also been aided by a wealth of third-party projects—libraries, add-ons, and complementary development efforts—that extend the language to an ever widening range of use cases.
Some of these projects, like PyInstaller and WxPython, shine for Python developers who are building desktop and end-user apps. Others, like PyPy, are used to give server-side Python apps extra oomph. And others, like PBR, CFFI, and MyPy, are useful for developing all kinds of Python apps, no matter where they might run.