OpenAI has achieved several key milestones since its founding in 2015:

1. 2015: OpenAI is founded in San Francisco by Sam Altman, Elon Musk, and others with the mission of ensuring artificial general intelligence benefits humanity.
2. 2018: Introduction of GPT (GPT-1), a large language model with 117 million parameters trained on 8 million web pages.
3. 2019: Release of GPT-2, a more powerful version with 1.5 billion parameters trained on 40 GB of text.
4. 2020: Launch of GPT-3, a significantly larger model with 175 billion parameters trained on 570 GB of text.
5. 2021: Release of Codex, a 6 billion parameter model trained on code that powers GitHub Copilot.
6. 2022 September: Open-sourcing of Whisper, a neural network for robust speech recognition.
7. 2022 November: Launch of ChatGPT, based on GPT-3.5, which gained massive popularity and reached 1 million users within 4 days.
8. 2024 February: OpenAI reaches a projected annual revenue of over $2 billion, serving 92% of Fortune 500 companies and attracting 100 million weekly users.

OpenAI had experienced rapid growth and has had a significant impact on the AI landscape, from research breakthroughs to widely adopted commercial products.