Glossary
What is a citation source map?
A citation source map is the record of which URLs an AI engine actually retrieved when answering a question about your category. It is the more actionable half of a visibility audit, because it tells you where the answer is being written — which is usually not on your own site.
What does a real one look like?
Across ten WordPress plugin categories measured in September 2026, cited sources were overwhelmingly third-party listicles rather than vendor product pages. Of 56 source mentions recorded, 16 — roughly 29% — came from domains owned by plugin or SaaS vendors.
The most-cited single domain across the whole run belonged to a booking plugin company, and it was cited in the backup, LMS and translation answers. Categories it sells nothing in. It publishes “best X” listicles about other people’s categories and the engines quote them.
Do vendors appear in their own answers?
Sometimes, and it is worth watching. Four separate answers cited a vendor’s own domain in support of an answer that named that vendor at or near the top — OptinMonster in popups, LifterLMS in courses, NitroPack in caching, AdTribes in product feeds. Whether the self-citation causes the placement or merely accompanies it cannot be established from observation alone. What is clear either way is that the companies writing the category’s reference content are the companies appearing in the category’s answers.
What do you do with the map?
Two things. Work out which of the cited sources you are absent from and could plausibly appear in — a listicle you are missing from is a concrete, contactable target in a way that “improve our AI visibility” is not. And decide whether the category’s reference content is something you should be publishing yourself.
This is why off-site placement is roughly half of the work. Optimising your own product page is the smaller half, and in most categories it is not where the answer is coming from.
Part of the GEO glossary. The measurements referenced here come from the Plugin Visibility Index, which publishes its raw counts and its limits.