AEO vs SEO: how to get cited by ChatGPT, Perplexity and Google's AI answers

I added AEO and GEO to the search program I run once assistants started answering questions our pages used to answer. The first lesson was humbling: most of what gets a page cited is ordinary, well-executed SEO. The second was more useful. Framing it as AEO vs SEO hid that for months. A small set of deliberate choices about crawler access, answer structure and measurement decides whether assistants quote you correctly, or at all.

What is the difference between AEO and SEO?

SEO aims to rank a page and earn the click. AEO aims to have a page selected, quoted and cited inside a generated answer, where the click is optional. Both depend on crawlable, indexed, trustworthy pages. They differ in how you shape content, which crawlers matter and how you measure success.

The timeline explains the urgency. Google rolled out AI Overviews in the US in May 2024, OpenAI launched ChatGPT search in October 2024, and Google opened AI Mode to all US users in May 2025. In under two years, the answer above the links became normal.

GEO, generative engine optimization, describes the same work, and most practitioners use the two terms interchangeably. I use AEO for the content practice and keep the crawler and measurement work under SEO, because that is where it lives in the codebase.

What does Google require for AI Overviews and AI Mode?

Google says there are no additional requirements. To be shown as a supporting link in AI Overviews or AI Mode, a page must be indexed and eligible to appear in Search with a snippet. You don't need special schema, an AI text file or new markup, and the usual snippet controls apply.

That has three practical consequences:

1. Snippet controls cut both ways. nosnippet, data-nosnippet and max-snippet limit what AI features can show from a page. Use them deliberately on content that must not be quoted without context, and nowhere else.
2. Google-Extended does not control Search. It is a robots.txt token for Gemini model training and grounding. Google says it does not affect inclusion or ranking in Google Search.
3. The traffic is already in Search Console. Google counts clicks and impressions from AI features in the Performance report under the Web search type. You can't separate them there yet, but they aren't missing.

How do ChatGPT and Perplexity find pages to cite?

Both run their own crawlers, with separate user agents for search indexing, model training and user-initiated fetches. Blocking a training crawler does not have to remove you from their answers. Which bots you allow is a policy decision, and robots.txt lets you make it bot by bot.

A robots.txt that allows AI search citations while opting out of model training looks like this:

User-agent: OAI-SearchBot
Allow: /

User-agent: PerplexityBot
Allow: /

User-agent: GPTBot
Disallow: /

User-agent: Google-Extended
Disallow: /

OpenAI notes that robots.txt changes can take about 24 hours to affect its systems. Check your CDN as well. Several CDNs and WAFs, Cloudflare among them, offer AI-bot blocking that applies regardless of robots.txt, and a single toggle there can undo the file above.

How do you write content that AI answers quote correctly?

Put the answer first. Open each section with a 40 to 60 word statement that would still be accurate and complete if quoted on its own, then support it with detail, evidence and examples. Use question-shaped headings, name things precisely and cite primary sources.

No answer engine publishes a formula, so treat these as practices that make passages easy to extract and hard to misquote:

1. Answer-first paragraphs. The first paragraph under a heading answers the heading.
2. Headings that match real questions. Use the words people type or say, not internal jargon.
3. Self-contained sentences. "As mentioned above" and "this approach" mean nothing when a single passage is lifted out.
4. Tables for comparisons. Structured rows are easy to parse and hard to paraphrase badly.
5. Dated, sourced facts. "Since October 21, 2024" beats "recently," and a named primary source beats "studies show."
6. A real author. A named person with a profile page, consistent across the site's Person and Organization markup.
7. Visible updates. Change the modified date only when the content actually changes.

In a regulated business, the third point matters most. An assistant that quotes "the policy covers water damage" without "caused by a sudden burst pipe" has created a compliance problem from an accurate page. That is why structured data for insurance websites and FAQ answers need their qualifiers inside the sentence.

Do you need llms.txt or special AI markup?

Not for Google. Its documentation says no special AI text files or markup are needed to appear in AI features. llms.txt is a community proposal for giving language models a curated map of a site. Adding one is harmless, but none of the crawler documentation cited here asks for it, so don't expect it to replace crawlable HTML.

Structured data still helps in the ordinary way. Consistent Organization, Person and Article markup makes it easier for any system to connect a page to the right company and author. It is not an AEO switch.

How do you measure AEO?

Track three signals: referral visits from AI assistants in your analytics, citation presence for a fixed set of priority questions checked on a schedule, and Search Console totals, which already include AI Overviews and AI Mode. Expect undercounting, because some AI-driven visits arrive with no referrer.

• Referrals. ChatGPT adds utm_source=chatgpt.com to many outbound links, which GA4 reports as chatgpt.com / referral. In GA4, create a custom channel group called "AI assistants" that matches sources such as chatgpt.com, perplexity.ai, gemini.google.com and copilot.microsoft.com.
• A citation panel. Pick 20 to 50 questions your customers actually ask. Each month, run them in the assistants that matter to you and record whether your site is cited, and whether the quote is accurate. Answers vary by user and session, so read the trend, not a single run.
• Search Console. Watch impressions and clicks for the pages behind those questions. Rising impressions with falling clicks is often the signature of an AI answer sitting above your result.

Report these as their own line, next to the business outcomes described in measuring SEO ROI for leadership. Don't fold them into organic traffic, where they will be invisible.

AEO vs SEO: a checklist that starts with SEO

• The page is indexed, canonical and eligible for a snippet in Google.
• robots.txt and the CDN allow the AI search crawlers you want, and your policy for training crawlers is written down.
• Each important section opens with a self-contained answer of about 40 to 60 words.
• Headings are phrased the way people ask.
• Facts carry dates and link to primary sources.
• The author is a named person with a profile page and consistent schema.
• AI referrals have their own channel group in analytics.
• A monthly citation panel covers your priority questions.