ChatGPT

A conversational AI interface developed by OpenAI, based on the GPT family of large language models.

How it works

ChatGPT sits on top of OpenAI's GPT models, which are fine-tuned with RLHF to behave helpfully in a conversational format. The interface maintains a running conversation history that is included in every API call as context. Newer versions support multimodality (images, documents, voice) and tool use (web browsing, code execution, image generation), which are triggered by the model emitting structured function calls that the platform handles before resuming generation.

Why it matters

ChatGPT's launch in November 2022 marked the moment AI became a mainstream phenomenon. It reached 100 million users in two months — the fastest product growth in history at the time — and triggered a global race among technology companies to deploy conversational AI. It fundamentally changed public expectations of what computers can do and accelerated regulatory, academic, and enterprise attention to AI by years.