Short answer
AI answer tools work in two steps: they gather sources, then write an answer from them. GEO works on both. First it makes sure your pages can be found and fetched at all; then it makes them easy to quote accurately once they are.Step 1: getting retrieved
Before an AI tool can use your page, it has to reach it. ChatGPT, Claude and Perplexity read the web through their own crawlers, and a robots.txt rule or a security setting can shut any of them out. Google's AI features work from its search index; Google says AI Overviews and AI Mode “may use a ‘query fan-out’ technique — issuing multiple related searches across subtopics and data sources” (Google Search Central).
Pages also have to be readable once fetched. Vercel found that “none of the major AI crawlers currently render JavaScript” (Vercel), so text that only appears after scripts run may not be seen at all.
Step 2: getting used in the answer
From the sources it gathers, the tool picks passages and facts to build its reply. Short, self-contained passages that answer one question are easy to lift. Long paragraphs that circle the point get summarized instead, and a summary is less likely to carry your name.
The research that named GEO tested which changes help. Adding citations, quotations and statistics raised a page's visibility in AI answers by up to 40% in the authors' benchmark, and they noted the effect “varies across domains” ( Aggarwal et al., KDD 2024).
Step 3: being believed
Tools compare what different sources say. If your site, your Google Business Profile and other listings agree on who you are and what you do, and other people mention you too, you are a safer thing to repeat. If they disagree, you are a risk.
What GEO can't do
It can't guarantee a mention. The tools change, answers vary between people, and nobody outside these companies controls them. What it does is remove the reasons a tool would skip you.