Glossary of AI search terms

document or standardproposalconventionresearch papervendor word

proposal

A text file at the root of a site: a name, a short summary and lists of links to the main material. Written for an AI agent. Proposed by Jeremy Howard in September 2024; the second edition came out on August 10, 2026. It is not an IETF or W3C standard.

More: What is llms.txt, the format.

convention

A file with the full text of a site’s material in one document. It is not in the llms.txt proposal: documentation platforms established the name.

More: What is llms-full.txt.

standard

A file with access rules for robots, described in RFC 9309. It says where robots may go, not what is useful.

More: AI crawlers and robots.txt.

standard

A list of site addresses for search robots. It helps discover pages and does not rate their importance.

convention

A simple text format: headings, lists, links and tables are marked with ordinary characters. Convenient for a person and for a program.

More: Markdown versions of pages.

search engine documentation

A machine-readable description of a page: what is on it and which properties it has.

More: Structured data and JSON-LD.

shared vocabulary

A vocabulary of types and properties for structured data: Product, Article, Organization, price, author. Founded in 2011 by the search engines Google, Bing, Yahoo and Yandex.

W3C recommendation

A format for writing structured data: a separate block in the page code. Google recommends it. The other formats are Microdata and RDFa.

owner documentation

A program that walks sites and downloads pages. AI companies run crawlers of three classes: for model training, for a search index, and for a specific user’s request.

More: AI crawlers and robots.txt.

convention

A program built on a language model that searches, reads pages and performs actions on a person’s request. It differs from a crawler in that it comes for the answer to a specific question.

open protocol

Model Context Protocol - a protocol through which an AI application connects to external data and tools. It is not directly related to llms.txt.

More: llms.txt and MCP.

convention

The amount of text a model can take into account at once. It is limited, which is why short maps and clean text without service markup suit an agent.

research paper

Generative Engine Optimization - optimization for generative search systems. The term was introduced in a 2023 research paper. What is measured is the share and position of a source in an answer.

More: GEO and AEO.

vendor word

Answer Engine Optimization - optimization for systems that answer rather than return a list of links. Its origin is attributed to 2017; the primary source is not confirmed.

vendor word

Large Language Model Optimization. Used as a synonym of GEO. No primary source was found.

vendor word

An ambiguous term. The first meaning is using AI in SEO work. The second is working on a site’s presence in AI answers. Without clarification it is unclear which one is meant.

vendor word

An umbrella name for a site’s presence in AI answers. It is not measured as such: bot requests, referrals, citations and share of voice are.

More: How to measure AI visibility.

convention

The share of answers that name a site or a brand over a fixed set of questions. A comparative metric.

convention

A link to a site in an AI answer as a source of facts.

product name

A block with an answer above the results in Google Search. Introduced on May 14, 2024. Search Console has no separate breakdown for it.

product name

A mode of Google Search with a dialog instead of a list of links. Introduced on March 5, 2025.

vendor word

The idea of a web where agents, not people, perform a large share of actions. Microsoft brought the word into use in May 2025.

category name

An experimental category of audits in Lighthouse that includes the llms.txt audit.

More: Lighthouse and llms.txt.

In its guide Google writes that AEO and GEO are terms you may see used, while optimizing for AI features of Search is still SEO. The company does not treat it as a separate discipline.