Python 0.9.0 Released by Guido van Rossum
In February 1991, Guido van Rossum, then at Centrum Wiskunde & Informatica in Amsterdam, publicly released Python 0.9.0 by posting it to the alt.sources newsgroup. The language offered an accessible, readable syntax and became foundational infrastructure for scientific computing and, later, machine learning research and tooling.
Background
By the late 1980s, scientific and research computing was dominated by languages that rewarded specialists. Fortran and C were fast, but writing them demanded careful attention to memory, types, and low-level detail that had little to do with the problem a researcher was actually trying to solve. Shell scripting could glue programs together, but broke down quickly on anything complex. A language called ABC, developed at Centrum Wiskunde & Informatica (CWI) in Amsterdam, had tried to make programming more readable and teachable, but it was difficult to extend and never spread far beyond its research context.
Guido van Rossum had worked on ABC at CWI and understood both what it did well and where it fell short. During the Christmas break of 1989, he started building something new: a language that kept ABC’s emphasis on clean, readable code, but opened up where ABC had closed down. It could call C code directly, slot into the Unix environment researchers already used, and be extended without asking permission from anyone.
What happened
Van Rossum posted Python 0.9.0 to the Usenet newsgroup alt.sources in February 1991, from CWI. Usenet was the main channel for sharing software and ideas across the early internet, and alt.sources was where programmers put things they wanted others to pick up and try. The post made the code publicly available to anyone with a connection.
The release already included features that would define the language for decades: exception handling, functions as first-class objects, and a module system for organising code. The syntax used indentation to mark the structure of a programme, which meant the visual layout matched the logical layout. There were no curly braces, no end keywords. The Python Software Foundation later quoted van Rossum explaining that he wanted a language where reading someone else’s code was not an ordeal.
None of this was aimed at artificial intelligence specifically. Python 0.9.0 was a general-purpose tool, released on permissive terms, built for people who needed to write programmes without fighting the language to do it. That quality, readable code that other people could pick up and modify, turned out to suit scientific computing well. Over the following years, researchers building numerical and statistical tools reached for Python because it let them express ideas quickly and share them in a form that colleagues could actually read. That made it, much later, the natural home for machine learning libraries. But in February 1991, it was simply a new language posted to a newsgroup by one programmer at a Dutch research institute.
Why it mattered
Python's readable syntax and permissive licence lowered the barrier to writing and sharing computational research, eventually making it the dominant language for machine learning libraries such as NumPy, scikit-learn, TensorFlow, and PyTorch. Its design philosophy, prioritising human comprehension over machine efficiency, proved well suited to the rapid prototyping cycles of AI research. Without a widely adopted, accessible scripting language of this kind, the dissemination of AI tooling across academia and industry would have been considerably slower.
People
Organisations
Centrum Wiskunde En Informatica
Sources
- Original Python 0.9.0 posting to alt.sources, February 1991.The Unix Heritage Society Usenet Archive.Primary source
- The Mind at Work: Guido van Rossum on How Python Makes Thinking Easy.Dropbox Blog.Secondary
- Python General FAQ. Why was Python created in the first place?.Python Software Foundation.Official
Cite this page
AI Achievements. (1991). Python 0.9.0 Released by Guido van Rossum. Retrieved 2026-08-22, from https://achievements.ai/milestone/python-developed-by-guido-van-rossum
@misc{achievements_python_developed_by_guido_van_rossum,
title = {Python 0.9.0 Released by Guido van Rossum},
author = {{AI Achievements}},
year = {1991},
url = {https://achievements.ai/milestone/python-developed-by-guido-van-rossum}
}