ChatGPT

ChatGPT is a chat-based product built on OpenAI's GPT family of models, refined for dialogue with reinforcement learning from human feedback. A user submits a prompt in natural language and the model generates a single conversational reply, drawing on patterns learned from training data plus, when enabled, live web search and connected tools such as file uploads or third-party plugins. It is accessed at chatgpt.com, through the ChatGPT mobile and desktop apps, or programmatically via the OpenAI API that developers use to embed the same models in their own products, per OpenAI's own help documentation. It is not a search index: there is no crawl, no ranked results page, and no guarantee that any given brand or page is mentioned in a reply, even if that page ranks well in Google. That absence of a ranking mechanism is exactly why AI-visibility and GEO tools in this directory treat ChatGPT as a surface to sample rather than a rank to track. They send test prompts and record whether and how a brand is mentioned in the generated answer, the same way they sample Perplexity, Gemini or Claude. Where it breaks: responses are non-deterministic across runs, so a single sampled prompt is a data point, not a verdict, which is why the tools in this corpus that track ChatGPT typically repeat prompts across many runs rather than trusting one reply.