// glossary
Glossary
Plain-English definitions for the terms that matter in AI search and SEO.
AI answer engine
An AI answer engine is a tool that responds to queries with a generated, direct answer rather than a list of links, including ChatGPT, Perplexity, and Google AI Overviews.
Read definition →Answer Engine Optimization (AEO)
AEO is the practice of making a site readable by AI answer engines like ChatGPT, Perplexity, and Google AI Overviews, built on top of standard SEO fundamentals.
Read definition →Legibility Score
Rankport's Legibility Score is a 0-100 metric that measures how readable a site is to both search engines and AI answer engines, across four sub-scores.
Read definition →llms.txt
llms.txt is a plain-text file at the root of a website that tells AI and LLM crawlers what the site is and points them to key content, improving AI legibility.
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