GPT-3.5 / ChatGPT
OpenAI · November 2022
Why It Matters
Brought AI to the mainstream. Reached 100 million users in 2 months — the fastest-growing consumer application in history at the time. Sparked a global AI arms race among tech companies.
Description
The model behind ChatGPT — the chatbot that brought AI to the mainstream. Built on GPT-3's foundation with RLHF (reinforcement learning from human feedback) to make it conversational, helpful, and safe. Its free chat interface made powerful AI accessible to anyone with a web browser for the first time.
Notable Milestones
- ▸Reached 100 million users faster than any consumer app in history
- ▸Triggered Google to declare a 'code red' and accelerate AI efforts
- ▸Used by students, writers, and professionals worldwide for writing, brainstorming, and learning
- ▸Inspired every major tech company to launch competing AI chatbots
Benchmark Scores
Key Innovations
Family Tree
Built On
Lineage
Successors (1)
Related Research (2)
Pioneered the RLHF paradigm — training a reward model from human preferences, then using it to fine-tune policies via reinforcement learning.
Applied RLHF to GPT-3: supervised fine-tuning → reward modeling → PPO optimization. Made models safer, more helpful, and more aligned.