Source authority is how much an AI or search system trusts a particular website as a reliable source on a given topic. It is shaped by signals such as topical depth, accuracy, recognition from other trusted sources, and a track record of credible content, rather than by any single number.
For brands, source authority helps explain why some domains get cited far more than others in AI answers. Certain sources, such as Wikipedia, established review platforms, and well-known publications, carry disproportionate trust for specific kinds of queries. The practical implications are twofold: build your own authority over time through depth and accuracy, and earn presence on the high-authority third-party sources that AI systems already lean on for your category.