cpython

This is the official source code for Python 3.15, the popular programming language that millions of developers use to write web applications, data analysis tools, automation scripts, and much more. If you've ever installed Python on your computer or used it in a project, this repository contains the actual code that makes it work.

Python itself is written in a language called C, and this repository holds all of that C code along with Python's standard library (the built-in tools that come with every Python installation). When you download and install Python from python.org, you're getting a compiled version of what's stored here. This particular version is 3.15.0 alpha 2, meaning it's a very early test release of the next major Python version—developers use alpha releases to try out new features and find bugs before the final version ships.

The repository exists so that Python developers and contributors can see exactly how Python works under the hood, propose improvements, and fix bugs. If you want to compile your own version of Python from scratch or contribute a new feature to the language, you'd clone this repository, make your changes, run the test suite to ensure nothing broke, and submit your contribution. The README includes straightforward instructions for building Python on different operating systems (Unix, Linux, macOS, Windows, etc.) and options for optimizing the build for better performance.

For most people, you don't need to interact with this repository directly—you just install a pre-built version of Python. But for language maintainers, researchers experimenting with Python internals, or contributors who want to shape the future of the language, this is the central hub. The repository includes thousands of automated tests to catch regressions, detailed documentation about how to build and contribute, and a complete history of every change made to Python since its creation in 2001.