The Ryze AI glossary defines the vocabulary of AI search for ecommerce operators. Terms covered: Generative Engine Optimization (GEO) — Generative engine optimization (GEO) is the practice of structuring and publishing content so that generative AI systems — ChatGPT, Perplexity, Google's AI Overviews, Claude — retrieve it, quote it accurately, and cite the source. Where classic SEO competes for a position in a list of ten blue links, GEO competes to be the passage an AI model lifts into its answer. The unit of success is not a ranking but an inclusion: was your sentence used, and was your brand named alongside it. Answer Engine Optimization (AEO) — Answer engine optimization (AEO) is the practice of structuring content so that systems which return a single direct answer — AI assistants, featured snippets, voice assistants, AI Overviews — return yours. It assumes the user will never see a list of results. There is one answer, and either it is drawn from your page or it is not, which makes AEO a binary outcome rather than a gradual climb up a ranking. AI Citation — An AI citation is an instance where an AI assistant attributes part of its generated answer to a specific source, usually as a linked reference. It is the AI-search equivalent of a ranking position and the primary success metric of generative engine optimization. Being cited is stricter than being mentioned: a mention names your brand, whereas a citation credits your page as the source of a claim and gives the reader a route to it. AI Visibility — AI visibility is the extent to which a brand, product or page appears in answers generated by AI assistants such as ChatGPT, Perplexity, Claude and Google's AI Overviews. It combines three things: how often you are mentioned across a defined set of queries, whether you are cited with a link, and how favourably you are characterised when you appear. Unlike search rankings, it is not reported anywhere — it exists only if you measure it. Structured Data for AI — Structured data for AI is schema markup — normally JSON-LD following the schema.org vocabulary — used to make a page's meaning explicit to machines, including the retrieval systems behind AI assistants. It states unambiguously what a page is and what its key facts are, so a model does not have to infer them from prose. It improves how reliably your content is parsed and repeated. It does not, by itself, make an assistant choose you. llms.txt — llms.txt is a proposed standard: a plain-text, markdown-formatted file placed at the root of a domain (at /llms.txt) that gives large language models a curated, human-written map of the site's most important content. It is a hand-picked index with short descriptions and links, designed to be read directly by a model rather than crawled. It is emphatically not a robots.txt for AI — it grants nothing and blocks nothing. Published by Ryze AI (get-ryze.ai).