Passage Ranking
When a search engine surfaces one relevant passage from a long page rather than judging the page as a whole. Clear headings are what make a passage findable in isolation.
Related terms
Unsupervised Learning
Training a model on unlabelled data and letting it find structure by itself — grouping similar customers, say, without being told what the groups are.
RDFa
Another attribute-based markup standard for embedding machine-readable facts in a page. Less common on business websites than JSON-LD, and largely equivalent in what it can express.
LLM (Large Language Model)
The kind of AI behind ChatGPT, Claude and Gemini. It is trained on an enormous amount of text and predicts what should come next, which is enough to answer questions, summarise, translate and write.
GPTBot
OpenAI’s crawler for building its index. Blocking it in robots.txt keeps your content out of that index — and out of the answers built from it.
Answer Engine
An answer engine replies to a question with a written answer instead of a list of links. ChatGPT, Perplexity and Google’s AI Overviews are all answer engines. The old question was “do we rank?”; the new one is “are we the answer?”
PerplexityBot
Perplexity’s crawler. Perplexity cites its sources prominently, so being readable by it is one of the more direct routes to a visible citation.