Perplexity

Definition

An AI answer engine that always retrieves live web sources and shows numbered inline citations for every claim.

Perplexity is built around retrieval: it searches the web for each query, synthesises an answer and attaches visible citations, making it one of the most transparent AI engines to optimise for. Because its answers are grounded in freshly fetched pages, strong performance depends on being crawlable, clearly structured and quotable on the specific question. It is a valuable proving ground for GEO because you can see exactly which sources it chose and reverse-engineer why.