How do AI answer engines choose which sources to cite?

No engine publishes exact rules; research and observed behavior point to retrievability, direct quotability, attribution, freshness, and authority as the main factors.

No AI engine publishes its exact source-selection rules, so honest answers describe research findings and observed behavior rather than guarantees. The published KDD 2024 GEO study found that content changes such as adding citations, quotations, and statistics measurably improved source visibility in generative engine answers, with the largest gains for lower-ranked sites. Engines generally retrieve candidate pages with a search layer, then select and compress passages that directly answer the question with attributable numbers or statements. Practical implications: answer the question in the first sentence, keep facts verifiable with primary sources, mark update dates, and keep pages free of obstacles to retrieval.