Loading
Guide · updated 2026-07-28
Four acronyms, one dependency chain. Each layer only pays off once the one beneath it works, so this page explains what each is, what SeoCheckup measures for it, and what to fix first.
SEO is the base: can a machine fetch your page, understand it, and decide it is worth surfacing. PSEO is SEO applied at scale, which mostly means keeping thousands of generated pages from collapsing into duplicates.
AEO changes the target. Instead of ranking a link, you are trying to be the passage an assistant quotes — which rewards extractability, clear structure and formats machines read cheaply. GEO is the layer above that: how your brand comes out across generative answers, including from sources you do not own.
None of them replaced the last one. A page that answer engines cannot fetch is invisible to all four.
SEO
SEO is making a page reachable, indexable and relevant enough that a search engine ranks it. Nothing about that has been replaced — every newer discipline below is built on top of it.
A search engine has to do three things before you can rank at all: fetch the page, understand it, and decide it is worth showing. Most sites that struggle are failing the first two, not the third.
Order matters when you fix things. A brilliant title on a page that robots.txt blocks is worth nothing, so crawl access comes before on-page work, which comes before chasing links.
PSEO
Programmatic SEO generates a page per combination of some dimensions — tool × language, city × service, integration × platform — to capture long-tail queries at a scale nobody could write by hand.
It works when each generated page genuinely answers a different question. It fails when the only thing that changes between pages is a swapped noun, because search engines classify the rest as duplicate and quietly drop them.
The failure mode is rarely a penalty. It is that a few thousand pages get crawled once, judged thin, and never revisited — which also burns the crawl budget you needed for the pages that do matter.
AEO
AEO is optimizing to be quoted inside an AI-generated answer rather than listed as a blue link. Ranking gets you considered; being extractable, self-contained and current gets you cited.
The single biggest blocker is technical, not editorial: most answer engines do not execute JavaScript. If your copy is rendered client-side, they fetch your page and see an empty shell.
The second is format. Answer engines parse Markdown far more reliably than HTML, and it costs roughly 60–80% fewer tokens to read. That is why serving a Markdown twin of each page — the same content at /page.md, or at the same URL when the request sends Accept: text/markdown — has turned into a real convention with a published specification behind it.
The third is shape. A passage that makes sense on its own, under a heading phrased the way a person would ask the question, is what actually gets lifted into an answer.
GEO
GEO is the strategic layer above AEO: not just whether one page can be cited, but how your brand is described across generative engines — including in sources you do not own.
AEO is a property of a page. GEO is a property of a reputation, and it is measured by asking engines real questions over time and watching which brands they name and how they frame them.
That cannot be derived from fetching one URL, which is why SeoCheckup does not print a GEO score. Inventing one from page signals would be a number with nothing behind it.
What a single-URL audit can do is verify the prerequisites. If ChatGPT's or Perplexity's crawlers cannot reach you, or your content only exists after JavaScript runs, no amount of GEO strategy will help — you are not in the candidate set at all.
SeoCheckup checks the technical prerequisites for GEO, not GEO itself. Measuring it needs prompt tracking across engines over time.
Run one audit. It scores all four layers on the same page — crawl access, on-page, security, AI crawler access and answer-engine readiness — and orders every finding worst-first, so the top of the list is where to begin.