ChatGPT
ChatGPT is OpenAI's conversational AI assistant — the consumer product that ignited the generative AI category in November 2022 and reached 900 million weekly active users by February 2026.
Why it matters
ChatGPT is the largest single AI assistant by weekly users, which makes it the most consequential answer engine for any brand pursuing AEO. The way ChatGPT describes your business — accurately, generically, or not at all — directly shapes how millions of customers research and compare options.
What it is
ChatGPT is OpenAI's chat product, built on the GPT family of large language models. It launched in November 2022 and reached 900 million weekly active users by February 2026 — the fastest-growing consumer software product in history.
How it answers questions
ChatGPT generates responses from the underlying model's training (subject to a knowledge cutoff) and, when web browsing is enabled, supplements with real-time search and citation links. The model synthesises information across multiple sources rather than returning ranked links, which is what makes it an answer engine.
Why it matters for AEO
- Scale — 900M weekly users means even a small share-of-voice gain compounds quickly.
- Synthesis — ChatGPT decides which brands to name and how to describe them; classical SEO doesn't reach into that decision.
- Citations — when ChatGPT cites third-party sources (G2, Wikipedia, news, review sites), those become the de-facto authority gates for your brand.
Model lineage
The product surfaces evolve across model versions (GPT-3.5, GPT-4, GPT-4o, GPT-5 family, reasoning variants like o1/o3). Each model update can shift how brands are described, so AEO measurement runs continuously rather than as a one-off check.
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