A conversational AI assistant developed by OpenAI, built on the GPT family of large language models and aligned with human preferences through RLHF — designed for natural, multi-turn dialogue and a wide range of text-based tasks.
In Depth
ChatGPT is the product interface that brought large language model capabilities to mainstream audiences. Launched by OpenAI in November 2022, it reached 100 million users within two months — the fastest product adoption in consumer internet history at the time. Built on the GPT (Generative Pre-trained Transformer) series, ChatGPT is distinguished from the raw base model by extensive fine-tuning and RLHF alignment, which shapes it to be helpful, harmless, and honest in conversational contexts.
Under the hood, ChatGPT is a next-token prediction model fine-tuned to follow instructions and engage in dialogue. The RLHF process involves human labelers rating model responses, training a reward model from those ratings, and then using reinforcement learning to maximize the reward signal. This transforms a probabilistic text predictor into a system that adapts its style, tone, and content to what users actually want — and avoids generating harmful content in most cases.
It is important to distinguish between ChatGPT (the product) and GPT-4 (the underlying model). ChatGPT can use different model versions — GPT-3.5 for free users, GPT-4 for subscribers — and adds features like memory, web browsing, image generation (via DALL-E), code execution, and plugin integrations. ChatGPT represents a broader trend toward AI assistants as interfaces to foundation model capabilities, a paradigm now replicated by Claude (Anthropic), Gemini (Google), and Copilot (Microsoft).
ChatGPT demonstrated that a powerful language model, properly aligned with human preferences, could be productized into an accessible, useful tool — triggering a wave of AI assistant development across the entire technology industry.