What this means
Perplexity's answer-engine and AI search ecosystem.
Historical record
Perplexity introduces Q2D-Web for large-scale retrieval evaluation in agentic RAG
The visible user prompt is not necessarily the query a source competes for. AI visibility therefore depends on several distinct stages: query reformulation, first-stage retrieval, ranking, evidence selection, and eventual citation.
Perplexity launches its answer engine
It helped establish the answer-engine model that later drove GEO, citation tracking and AI visibility measurement.