How AI engines actually decide what to cite (ChatGPT, Perplexity, Gemini, AI Overviews)

Everyone keeps asking "is SEO dead." Wrong question. AI search doesn't show ten blue links. It generates one answer and names a few brands. If you're not in that answer, you don't exist for that query. So the real question is: how do these engines decide who to name? I went down a rabbit hole on how four of them actually retrieve and cite sources. Here's what's true in 2026, with real numbers. ChatGPT: being known beats ranking ChatGPT answers in two modes. Default mode answers fro...