This is Tkinter tutorial. It covers the basics of GUI programming in Python with Tkinter. The tutorial is suitable for beginners and intermediate programmers. The examples are written in OOP. Sources and images are available at author's Github Tkinter-Examples repository.
Table of contents
Tkinter is a Python binding to the Tk GUI toolkit. Tk is the original GUI library for the Tcl language. Tkinter is implemented as a Python wrapper around a complete Tcl interpreter embedded in the Python interpreter.
A unique e-book Tkinter programming is available on ZetCode; in PDF format with 200 pages and 89 code examples.
The Tkinter tutorial - procedural style is a Tkinter tutorial in procedural programming style. Calculating the Pi number in Tkinter is covered in Long-running task in Tkinter. There is a full Python tutorial on ZetCode. The original Tk toolkit in Tcl language is covered in Tcl/Tk tutorial. Tutorials for other GUI toolkits for Python language are PyQt5 tutorial, wxPython tutorial, and Python Gtk tutorial.