Microsoft CEO Satya Nadella, pictured right, hired Sam Altman, left, after his surprise ouster as head of OpenAI
Microsoft CEO Satya Nadella, pictured right, hired Sam Altman, left, after his surprise ouster as head of OpenAI AFP

Microsoft's hiring of ousted OpenAI CEO Sam Altman on Monday marks another twist in the seven-year-old partnership between the US giant and the startup that created ChatGPT.

Here a key moments in the history of their partnership:

OpenAI is founded in 2015 by entrepreneurs and investors, including Sam Altman, Greg Brockman and Tesla chief Elon Musk.

It is established as a not-for-profit organisation that publishes open source research and software available to all.

Musk quits the project in 2018 following clashes with the board of directors.

Altman transforms OpenAI into a "capped profit" company and seeks new investors.

In 2019, Microsoft invests $1 billion in OpenAI, largely in the form of computing credits, in exchange for a role in the future commercialisation of its technologies.

The goal for Microsoft is to develop its cloud offering, where it competes with Google (Alphabet) and Amazon.

OpenAI launches GPT-3 in 2020, the third version of its large-scale language model, trained on huge volumes of text scraped from the internet by Microsoft's computing infrastructure.

This model is far more powerful than its competitors, with some 175 billion parameters.

Microsoft in 2020 says it has built a supercomputer exclusively designed to train large OpenAI models.

Its cloud network, Azure, can now make these systems available to Microsoft customers.

OpenAI in 2021 says it has developed DALL-E, an AI model capable of generating images when provided with descriptions.

OpenAI achieves worldwide attention with the November 2022 launch of ChatGPT, a language model open to the public, initially available free of charge.

In January 2023, Microsoft announces "an investment of several billion dollars over several years" -- $10 billion, according to US media.

It says it is "investing in the development of specialised supercomputer systems" for its partnership with OpenAI, but makes no mention of acquiring a stake in its capital.

According to US media, Microsoft had sought to buy 49 percent of OpenAI, in an offer that valued it at $29 billion.

In March 2023, Microsoft says it is integrating the GPT-4 version of OpenAI into its consumer products such as search engine Bing, Outlook email and Office suite (Word, Excel), but will charge users extra.

Microsoft is not notified of the OpenAI board's decision on Friday to dismiss Sam Altman, according to US press reports.

After trying over the weekend to get him reinstated, the group announces that it is hiring him and co-founder Greg Brockman.

The latter suggest that they will continue to create AI products at Microsoft, and Brockman announces the recruitment of several key OpenAI managers for these projects.