How is Python interpreted with wxPython, PyQt, PySide or Tkinter?

This is just a really generalized high-level explanation about "GUI toolkits"...

Lets say you decide to use the Qt framework. This framework is written in C++. There are two different python bindings that can be used, allowing one to write a GUI application in python against the same API as the C++ version.

The python bindings provide a wrapping around calls into the C++ code. PyQt4 for instance uses sip, while PySide uses shiboken. These are just language wrapping tools that take specifications for how to map between the C++ objects and their intended python interface.

Ok, so you start using PyQt... All of the code you write has to pass through the python interpreter. Some of it may be pure python. Some of it will call into C++ libs to create things like your widgets. In Qt, there will be a C++ pointer associated with the python instance counterpart.

It is the C++ layer that is then communicating with the window manager of your platform, to turn platform-independent API calls into something platform specific, like how to exactly draw a button or menu.

Whether you create a console only or GUI based python application, it all goes through the python interpreter to interpret your python code. Something must interpret the python language for you.