What is answer engine optimization?
Answer engine optimization (AEO) is the work of making a business's content easy for AI search tools to find, understand, and cite. An answer engine responds to a question with a written answer and a few source links, instead of a list of ten results. The goal of AEO is to be one of those sources.
AEO is an industry term. The Google, OpenAI, and Perplexity guides for site owners describe how each system finds and cites web pages without using it, and those guides are what AEO work is based on.
What are answer engines?
The answer engines most people use are:
- Google AI Overviews: AI-written summaries at the top of some Google results. Google says they "are only shown when our systems determine that it is additive to classic Search, and as such, often don't trigger."
- Google AI Mode: a conversational Google search mode for questions that need "further exploration, reasoning, or complex comparisons."
- ChatGPT search: ChatGPT's web search, which cites and links the pages it uses.
- Perplexity: an AI search engine that links the pages it uses in its answers.
How do answer engines choose sources?
Each engine finds pages through its own search system, then cites pages that help answer the question:
- Google uses its normal search index. To be shown as a supporting link in AI Overviews or AI Mode, a page "must be indexed and eligible to be shown in Google Search with a snippet." Both features may use a "query fan-out" technique, issuing multiple related searches across subtopics to build a response.
- ChatGPT uses a crawler called OAI-SearchBot to surface websites in ChatGPT's search features. OpenAI says sites that block OAI-SearchBot "will not be shown in ChatGPT search answers, though can still appear as navigational links."
- Perplexity uses PerplexityBot, which "is designed to surface and link websites in search results on Perplexity."
Their guides explain how to be eligible rather than which page gets cited: be crawlable, be indexed, and answer the question well.
How is AEO different from SEO?
The difference is the result, not most of the work. SEO aims for a ranked position in a list of links. AEO aims for a citation inside a written answer, where only a few sources appear.
Google is direct about the overlap. Its guidance for AI features says: "The best practices for SEO remain relevant for AI features in Google Search (such as AI Overviews and AI Mode). There are no additional requirements to appear in AI Overviews or AI Mode, nor other special optimizations necessary."
Where AEO adds work is outside Google. ChatGPT and Perplexity use their own crawlers, so a site has to let those crawlers in, and blocking them by accident, for example through a firewall or CDN setting, keeps the site out of those answers.
What does AEO work include?
Most of it is SEO groundwork that Google lists as still "worthwhile" for AI features:
- Allow crawling in robots.txt and in any CDN or hosting firewall, for Googlebot and for the AI search crawlers (OAI-SearchBot, PerplexityBot).
- Answer real questions clearly. Google's ranking systems "are designed to prioritize helpful, reliable information that's created to benefit people."
- Keep important content in text, not only in images or video.
- Make pages findable through internal links.
- Keep structured data consistent with the page. Google says structured data should match the visible text, and that no special schema.org structured data is needed for AI features.
- Keep the Google Business Profile up to date. Google lists this among the practices for AI features. See how Business Profile verification works.
Google also says: "You don't need to create new machine readable files, AI text files, or markup to appear in these features." For what that means for llms.txt, see what is llms.txt.
How do you measure AEO?
Answer engines don't offer a ranking report, so measurement is indirect:
- Google Search Console includes clicks and impressions from AI Overviews and AI Mode in the overall search traffic, in the Performance report under the "Web" search type.
- Analytics referrals: ChatGPT adds the parameter
utm_source=chatgpt.comto referral links, so ChatGPT visits show up as a source in tools such as Google Analytics. - Prompt testing: asking the same set of questions in ChatGPT, Perplexity, and Google on a schedule and recording which sites are cited. Google notes that AI Mode and AI Overviews may use different models and techniques, "so the set of responses and links they show will vary," so a single test is a snapshot, not a ranking.
Google also says clicks from results pages with AI Overviews are "higher quality (meaning, users are more likely to spend more time on the site)."