This guide covers how to contribute to CPython. It is known by the nickname of "the devguide" by the Python core developers.
The official home of this guide is https://devguide.python.org.
To render the devguide to HTML under _build/html, run:
make html
To render the devguide to HTML, and open the result in a browser, run:
make htmlview
To maintain a live view of edits as they are saved, run:
make htmllive