A “What is X” definition is the single sentence you would want an AI assistant to repeat verbatim if asked to describe your product cold. Writing it explicitly, in glossary style, and repeating it identically everywhere on your site removes the ambiguity that otherwise forces a model to synthesize (or mis-synthesize) your positioning from scattered marketing copy.
Why it matters for AEO. When someone asks an AI assistant "what is [your category]" or "what is [your product]", the model needs a clean, quotable definition. Pages that bury this in narrative prose get paraphrased loosely, or skipped in favor of a competitor's clearer one.
How to do it
- Open your product or category page with a single bolded sentence that defines the term the way a glossary would: "[Term] is a [category] that [core function], used by [audience] to [outcome]."
- Keep the definition under 40 words and free of adjectives that only make sense to someone who already knows your product.
- Repeat the exact same core definition across your homepage, about page, and category pages - inconsistent self-descriptions confuse extraction.
- Update the definition the moment your positioning genuinely changes, and update it everywhere at once.
How to verify. Ask an LLM "what is [your product]" with no other context and compare its answer to your own definition sentence - they should be nearly identical.
Example
"AskRank is an AEO/GEO visibility tracker that shows indie SaaS
founders how often ChatGPT, Claude, Perplexity, and Gemini
mention their brand."